45 Useful Oracle Queries

useful-oracle-queries

Here’s a list of 40+ Useful Oracle queries that every Oracle developer must bookmark. These queries range from date manipulation, getting server info, get execution status, calculate database size etc.

Date / Time related queries

  1. Get the first day of the month

    Quickly returns the first day of current month. Instead of current month you want to find first day of month where a date falls, replace SYSDATE with any date column/value.

    SELECT TRUNC (SYSDATE, 'MONTH') "First day of current month"FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  2. Get the last day of the month

    This query is similar to above but returns last day of current month. One thing worth noting is that it automatically takes care of leap year. So if you have 29 days in Feb, it will return 29/2. Also similar to above query replace SYSDATE with any other date column/value to find last day of that particular month.

    SELECT TRUNC (LAST_DAY (SYSDATE)) "Last day of current month"FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  3. Get the first day of the Year

    First day of year is always 1-Jan. This query can be use in stored procedure where you quickly want first day of year for some calculation.

    SELECT TRUNC (SYSDATE, 'YEAR') "Year First Day" FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  4. Get the last day of the year

    Similar to above query. Instead of first day this query returns last day of current year.

    SELECT ADD_MONTHS (TRUNC (SYSDATE, 'YEAR'), 12) - 1 "Year Last Day" FROM DUAL
    Code language: SQL (Structured Query Language) (sql)

  5. Get number of days in current month

    Now this is useful. This query returns number of days in current month. You can change SYSDATE with any date/value to know number of days in that month.

    SELECT CAST (TO_CHAR (LAST_DAY (SYSDATE), 'dd') AS INT) number_of_daysFROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  6. Get number of days left in current month

    Below query calculates number of days left in current month.

    SELECT SYSDATE,LAST_DAY (SYSDATE) "Last",LAST_DAY (SYSDATE) - SYSDATE "Days left"FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  7. Get number of days between two dates

    Use this query to get difference between two dates in number of days.

    SELECT ROUND ( (MONTHS_BETWEEN ('01-Feb-2014', '01-Mar-2012') * 30), 0)num_of_daysFROM DUAL;</p> <p>OR</p> <p>SELECT TRUNC(sysdate) - TRUNC(e.hire_date) FROM employees;
    Code language: SQL (Structured Query Language) (sql)

    Use second query if you need to find number of days since some specific date. In this example number of days since any employee is hired.

  8. Display each months start and end date upto last month of the year

    This clever query displays start date and end date of each month in current year. You might want to use this for certain types of calculations.

    SELECT ADD_MONTHS (TRUNC (SYSDATE, 'MONTH'), i) start_date,TRUNC (LAST_DAY (ADD_MONTHS (SYSDATE, i))) end_dateFROM XMLTABLE ('for $i in 0 to xs:int(D) return $i'PASSING XMLELEMENT (d,FLOOR (MONTHS_BETWEEN (ADD_MONTHS (TRUNC (SYSDATE, 'YEAR') - 1, 12),SYSDATE)))COLUMNS i INTEGER PATH '.');
    Code language: SQL (Structured Query Language) (sql)

  9. Get number of seconds passed since today (since 00:00 hr)

    SELECT (SYSDATE - TRUNC (SYSDATE)) * 24 * 60 * 60 num_of_sec_since_morningFROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  10. Get number of seconds left today (till 23:59:59 hr)

    SELECT (TRUNC (SYSDATE+1) - SYSDATE) * 24 * 60 * 60 num_of_sec_leftFROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

    Data dictionary queries

  11. Check if a table exists in the current database schema

    A simple query that can be used to check if a table exists before you create it. This way you can make your create table script rerunnable. Just replace table_name with actual table you want to check. This query will check if table exists for current user (from where the query is executed).

    SELECT table_nameFROM user_tablesWHERE table_name = 'TABLE_NAME';
    Code language: SQL (Structured Query Language) (sql)

  12. Check if a column exists in a table

    Simple query to check if a particular column exists in table. Useful when you tries to add new column in table using ALTER TABLE statement, you might wanna check if column already exists before adding one.

    SELECT column_name AS FOUNDFROM user_tab_colsWHERE table_name = 'TABLE_NAME' AND column_name = 'COLUMN_NAME';
    Code language: SQL (Structured Query Language) (sql)

  13. Showing the table structure

    This query gives you the DDL statement for any table. Notice we have pass ‘TABLE’ as first parameter. This query can be generalized to get DDL statement of any database object. For example to get DDL for a view just replace first argument with ‘VIEW’ and second with your view name and so.

    SELECT DBMS_METADATA.get_ddl ('TABLE', 'TABLE_NAME', 'USER_NAME') FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  14. Getting current schema

    Yet another query to get current schema name.

    SELECT SYS_CONTEXT ('userenv', 'current_schema') FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  15. Changing current schema

    Yet another query to change the current schema. Useful when your script is expected to run under certain user but is actually executed by other user. It is always safe to set the current user to what your script expects.

    ALTER SESSION SET CURRENT_SCHEMA = new_schema;
    Code language: SQL (Structured Query Language) (sql)

    Database administration queries

  16. Database version information

    Returns the Oracle database version.

    SELECT * FROM v$version;
    Code language: SQL (Structured Query Language) (sql)

  17. Database default information

    Some system default information.

    SELECT username,profile,default_tablespace,temporary_tablespaceFROM dba_users;
    Code language: SQL (Structured Query Language) (sql)

  18. Database Character Set information

    Display the character set information of database.

    SELECT * FROM nls_database_parameters;
    Code language: SQL (Structured Query Language) (sql)

  19. Get Oracle version

    SELECT VALUEFROM v$system_parameterWHERE name = 'compatible';
    Code language: SQL (Structured Query Language) (sql)

  20. Store data case sensitive but to index it case insensitive

    Now this ones tricky. Sometime you might querying database on some value independent of case. In your query you might do UPPER(..) = UPPER(..) on both sides to make it case insensitive. Now in such cases, you might want to make your index case insensitive so that they don’t occupy more space. Feel free to experiment with this one.

    CREATE TABLE tab (col1 VARCHAR2 (10));</p> <p>CREATE INDEX idx1ON tab (UPPER (col1));</p> <p>ANALYZE TABLE a COMPUTE STATISTICS;
    Code language: SQL (Structured Query Language) (sql)

  21. Resizing Tablespace without adding datafile

    Yet another DDL query to resize table space.

    ALTER DATABASE DATAFILE '/work/oradata/STARTST/STAR02D.dbf' resize 2000M;
    Code language: SQL (Structured Query Language) (sql)

  22. Checking autoextend on/off for Tablespaces

    Query to check if autoextend is on or off for a given tablespace.

    SELECT SUBSTR (file_name, 1, 50), AUTOEXTENSIBLE FROM dba_data_files;</p> <p>(OR)</p> <p>SELECT tablespace_name, AUTOEXTENSIBLE FROM dba_data_files;
    Code language: SQL (Structured Query Language) (sql)

  23. Adding datafile to a tablespace

    Query to add datafile in a tablespace.

    ALTER TABLESPACE data01 ADD DATAFILE '/work/oradata/STARTST/data01.dbf'SIZE 1000M AUTOEXTEND OFF;
    Code language: SQL (Structured Query Language) (sql)

  24. Increasing datafile size

    Yet another query to increase the datafile size of a given datafile.

    ALTER DATABASE DATAFILE '/u01/app/Test_data_01.dbf' RESIZE 2G;
    Code language: SQL (Structured Query Language) (sql)

  25. Find the Actual size of a Database

    Gives the actual database size in GB.

    SELECT SUM (bytes) / 1024 / 1024 / 1024 AS GB FROM dba_data_files;
    Code language: SQL (Structured Query Language) (sql)

  26. Find the size occupied by Data in a Database or Database usage details

    Gives the size occupied by data in this database.

    SELECT SUM (bytes) / 1024 / 1024 / 1024 AS GB FROM dba_segments;
    Code language: SQL (Structured Query Language) (sql)

  27. Find the size of the SCHEMA/USER

    Give the size of user in MBs.

    SELECT SUM (bytes / 1024 / 1024) "size"FROM dba_segmentsWHERE owner = '&owner';
    Code language: SQL (Structured Query Language) (sql)

  28. Last SQL fired by the User on Database

    This query will display last SQL query fired by each user in this database. Notice how this query display last SQL per each session.

    SELECT S.USERNAME || '(' || s.sid || ')-' || s.osuser UNAME,s.program || '-' || s.terminal || '(' || s.machine || ')' PROG,s.sid || '/' || s.serial# sid,s.status "Status",p.spid,sql_text sqltextFROM v$sqltext_with_newlines t, V$SESSION s, v$process pWHERE t.address = s.sql_addressAND p.addr = s.paddr(+)AND t.hash_value = s.sql_hash_valueORDER BY s.sid, t.piece;
    Code language: SQL (Structured Query Language) (sql)

    Performance related queries

  29. CPU usage of the USER

    Displays CPU usage for each User. Useful to understand database load by user.

    SELECT ss.username, se.SID, VALUE / 100 cpu_usage_secondsFROM v$session ss, v$sesstat se, v$statname snWHERE se.STATISTIC# = sn.STATISTIC#AND NAME LIKE '%CPU used by this session%'AND se.SID = ss.SIDAND ss.status = 'ACTIVE'AND ss.username IS NOT NULLORDER BY VALUE DESC;
    Code language: SQL (Structured Query Language) (sql)

  30. Long Query progress in database

    Show the progress of long running queries.

    SELECT a.sid,a.serial#,b.username,opname OPERATION,target OBJECT,TRUNC (elapsed_seconds, 5) "ET (s)",TO_CHAR (start_time, 'HH24:MI:SS') start_time,ROUND ( (sofar / totalwork) * 100, 2) "COMPLETE (%)"FROM v$session_longops a, v$session bWHERE a.sid = b.sidAND b.username NOT IN ('SYS', 'SYSTEM')AND totalwork > 0ORDER BY elapsed_seconds;
    Code language: SQL (Structured Query Language) (sql)

  31. Get current session id, process id, client process id?

    This is for those who wants to do some voodoo magic using process ids and session ids.

    SELECT b.sid,b.serial#,a.spid processid,b.process clientpidFROM v$process a, v$session bWHERE a.addr = b.paddr AND b.audsid = USERENV ('sessionid');
    Code language: SQL (Structured Query Language) (sql)

    • V$SESSION.SID AND V$SESSION.SERIAL# is database process id
    • V$PROCESS.SPID is shadow process id on this database server
    • V$SESSION.PROCESS is client PROCESS ID, ON windows it IS : separated THE FIRST # IS THE PROCESS ID ON THE client AND 2nd one IS THE THREAD id.
  32. Last SQL Fired from particular Schema or Table:

    SELECT CREATED, TIMESTAMP, last_ddl_timeFROM all_objectsWHERE OWNER = 'MYSCHEMA'AND OBJECT_TYPE = 'TABLE'AND OBJECT_NAME = 'EMPLOYEE_TABLE';
    Code language: SQL (Structured Query Language) (sql)

  33. Find Top 10 SQL by reads per execution

    SELECT *FROM ( SELECT ROWNUM,SUBSTR (a.sql_text, 1, 200) sql_text,TRUNC (a.disk_reads / DECODE (a.executions, 0, 1, a.executions))reads_per_execution,a.buffer_gets,a.disk_reads,a.executions,a.sorts,a.addressFROM v$sqlarea aORDER BY 3 DESC)WHERE ROWNUM < 10;
    Code language: SQL (Structured Query Language) (sql)

  34. Oracle SQL query over the view that shows actual Oracle connections.

    SELECT osuser,username,machine,programFROM v$sessionORDER BY osuser;
    Code language: SQL (Structured Query Language) (sql)

  35. Oracle SQL query that show the opened connections group by the program that opens the connection.

    SELECT program application, COUNT (program) Numero_SesionesFROM v$sessionGROUP BY programORDER BY Numero_Sesiones DESC;
    Code language: SQL (Structured Query Language) (sql)

  36. Oracle SQL query that shows Oracle users connected and the sessions number for user

    SELECT username Usuario_Oracle, COUNT (username) Numero_SesionesFROM v$sessionGROUP BY usernameORDER BY Numero_Sesiones DESC;
    Code language: SQL (Structured Query Language) (sql)

  37. Get number of objects per owner

    SELECT owner, COUNT (owner) number_of_objectsFROM dba_objectsGROUP BY ownerORDER BY number_of_objects DESC;
    Code language: SQL (Structured Query Language) (sql)

    Utility / Math related queries

  38. Convert number to words

    More info: Converting number into words in Oracle

    SELECT TO_CHAR (TO_DATE (1526, 'j'), 'jsp') FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

    Output:
    one thousand five hundred twenty-six

  39. Find string in package source code

    Below query will search for string ‘FOO_SOMETHING’ in all package source. This query comes handy when you want to find a particular procedure or function call from all the source code.

    --search a string foo_something in package source codeSELECT *FROM dba_sourceWHERE UPPER (text) LIKE '%FOO_SOMETHING%'AND owner = 'USER_NAME';
    Code language: SQL (Structured Query Language) (sql)

  40. Convert Comma Separated Values into Table

    The query can come quite handy when you have comma separated data string that you need to convert into table so that you can use other SQL queries like IN or NOT IN. Here we are converting ‘AA,BB,CC,DD,EE,FF’ string to table containing AA, BB, CC etc. as each row. Once you have this table you can join it with other table to quickly do some useful stuffs.

    WITH csvAS (SELECT 'AA,BB,CC,DD,EE,FF'AS csvdataFROM DUAL)SELECT REGEXP_SUBSTR (csv.csvdata, '[^,]+', 1, LEVEL) pivot_charFROM DUAL, csvCONNECT BY REGEXP_SUBSTR (csv.csvdata,'[^,]+', 1, LEVEL) IS NOT NULL;
    Code language: SQL (Structured Query Language) (sql)

  41. Find the last record from a table

    This ones straight forward. Use this when your table does not have primary key or you cannot be sure if record having max primary key is the latest one.

    SELECT *FROM employeesWHERE ROWID IN (SELECT MAX (ROWID) FROM employees);</p> <p>(OR)</p> <p>SELECT * FROM employeesMINUSSELECT *FROM employeesWHERE ROWNUM < (SELECT COUNT (*) FROM employees);
    Code language: SQL (Structured Query Language) (sql)

  42. Row Data Multiplication in Oracle

    This query use some tricky math functions to multiply values from each row. Read below article for more details.
    More info: Row Data Multiplication In Oracle

    WITH tblAS (SELECT -2 num FROM DUALUNIONSELECT -3 num FROM DUALUNIONSELECT -4 num FROM DUAL),sign_valAS (SELECT CASE MOD (COUNT (*), 2) WHEN 0 THEN 1 ELSE -1 END valFROM tblWHERE num < 0)SELECT EXP (SUM (LN (ABS (num)))) * valFROM tbl, sign_valGROUP BY val;
    Code language: SQL (Structured Query Language) (sql)

  43. Generating Random Data In Oracle

    You might want to generate some random data to quickly insert in table for testing. Below query help you do that. Read this article for more details.
    More info: Random Data in Oracle

    SELECT LEVEL empl_id,MOD (ROWNUM, 50000) dept_id,TRUNC (DBMS_RANDOM.VALUE (1000, 500000), 2) salary,DECODE (ROUND (DBMS_RANDOM.VALUE (1, 2)), 1, 'M', 2, 'F') gender,TO_DATE (ROUND (DBMS_RANDOM.VALUE (1, 28))|| '-'|| ROUND (DBMS_RANDOM.VALUE (1, 12))|| '-'|| ROUND (DBMS_RANDOM.VALUE (1900, 2010)),'DD-MM-YYYY')dob,DBMS_RANDOM.STRING ('x', DBMS_RANDOM.VALUE (20, 50)) addressFROM DUALCONNECT BY LEVEL < 10000;
    Code language: SQL (Structured Query Language) (sql)

  44. Random number generator in Oracle

    Plain old random number generator in Oracle. This ones generate a random number between 0 and 100. Change the multiplier to number that you want to set limit for.

    --generate random number between 0 and 100SELECT ROUND (DBMS_RANDOM.VALUE () * 100) + 1 AS random_num FROM DUAL;
    Code language: SQL (Structured Query Language) (sql)

  45. Check if table contains any data

    This one can be written in multiple ways. You can create count(*) on a table to know number of rows. But this query is more efficient given the fact that we are only interested in knowing if table has any data.

    SELECT 1FROM TABLE_NAMEWHERE ROWNUM = 1;
    Code language: SQL (Structured Query Language) (sql)

If you have some cool query that can make life of other Oracle developers easy, do share in comment section.

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55 Comments

  1. Madiraju Krishna Chaitanya says:

    Hi Viral Patel,Thanks a LOT for providing these useful Oracle Queries for us.Please keep up the Good Work.All the Best.

  2. Praveen says:

    very useful queries, thanks for sharing :)

  3. Tushar says:

    Excellent compilation of queries Viral!.
    You rock bhai :)

  4. krunal says:

    Thank you
    using above database queries i will solve db related problems in my many project.

  5. Harshita says:

    Good Job Viral, really useful article. Looking forward to more such stuff. :)

  6. Chandra says:

    Really Some useful queries …

  7. junaid ahmad says:

    Can you please give 50 different views of Data Dictionary in form of SQL Queries?

    • Nishant Mishra says:

      Use USER_Views

  8. Nishant Mishra says:

    You can use USER_VIEWS to see the available views with the SCHEMA.
    Describe the view and see the columns..
    Use the column name to get the details

  9. David says:

    I have a requirement.
    I have 5 attribute columns corresponding 5 days of the week from Monday to Friday.
    The attribute values can be Yes or No.

    If Wednesday and Friday are set to Yes, I need a query to retrieve all the wednesdays and Fridays from a given date to sysdate.

    Similarly, If Monday, Wednesday and Thursday are set to Yes, I need all the Mondays, Wednesdays and Thursday from a given date(passed as parameter) to sysdate.

    Could anyone please help me in writing this query?

    • Kevin says:

      for David’s question on April 17th..I’m sure this could probably be cleaned up some more and I see that the Friday portion of this returns a friday before 01/01/2012 but this is a start…

      create table CVT_T1_DAYS as
      (select '1' Mon, '0' Tue, '0' Wed, '1' Thu, '1' Fri from dual);
      
      select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
      from (SELECT 'MON' dd from CVT_T1_DAYS where mon = 1)
      connect by rownum &lt;= round((sysdate - to_date('01/01/2012', 'dd/mm/yyyy'))/7)
      union
      select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
      from (SELECT 'TUE' dd from CVT_T1_DAYS where tue = 1)
      connect by rownum &lt;= round((sysdate - to_date('01/01/2012', 'dd/mm/yyyy'))/7)
      union
      select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
      from (SELECT 'WED' dd from CVT_T1_DAYS where wed = 1)
      connect by rownum &lt;= round((sysdate - to_date('01/01/2012', 'dd/mm/yyyy'))/7)
      union
      select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
      from (SELECT 'THU' dd from CVT_T1_DAYS where thu = 1)
      connect by rownum &lt;= round((sysdate - to_date('01/01/2012', 'dd/mm/yyyy'))/7)
      union
      select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
      from (SELECT 'FRI' dd from CVT_T1_DAYS where FRI = 1)
      connect by rownum &lt;= round((sysdate - to_date('01/01/2012', 'dd/mm/yyyy'))/7)
      order by date_
      ;
      
      

      • Kevin says:

        note, the “<=” should be <=
        or "less than or equal to"

        it didn't format correctly in my cut/paste

  10. Fernando Tlatilolpa says:

    Hello and thanks Viral, I think you can include a query which return number of columns result of a dynamic query, these usefull when you send a script inside a function and you don’t know exactly how many columns you obtain.

    Once again thaks for your effort.

  11. salim says:

    Thank you dear for sharing knowledge

  12. Kevin says:

    in response to David’s query….cleaned up the dates that come out prior to the date entered as well as if you enter a date in the future. Both SQL and PL/SQL solutions are below. note, greater than, equal, less than formatting might be affected by the tags

    select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
    from (SELECT 'MON' dd from CVT_T1_DAYS where mon = 1)
    where to_date('&amp;indate', 'mm/dd/yyyy') &lt;= sysdate
          and   next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    connect by rownum &lt;= round((sysdate - to_date('&amp;indate', 'mm/dd/yyyy'))/7) 
            and next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    union
    select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
    from (SELECT 'TUE' dd from CVT_T1_DAYS where tue = 1)
    where to_date('&amp;indate', 'mm/dd/yyyy') &lt;= sysdate
          and   next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    connect by rownum &lt;= round((sysdate - to_date('&amp;indate', 'mm/dd/yyyy'))/7) 
            and next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    union
    select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
    from (SELECT 'WED' dd from CVT_T1_DAYS where wed = 1)
    where to_date('&amp;indate', 'mm/dd/yyyy') &lt;= sysdate
          and   next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    connect by rownum &lt;= round((sysdate - to_date('&amp;indate', 'mm/dd/yyyy'))/7) 
            and next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    union
    select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
    from (SELECT 'THU' dd from CVT_T1_DAYS where thu = 1)
    where to_date('&amp;indate', 'mm/dd/yyyy') &lt;= sysdate
          and   next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    connect by rownum &lt;= round((sysdate - to_date('&amp;indate', 'mm/dd/yyyy'))/7) 
            and next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    union
    select dd, next_day(sysdate - (rownum * 7), dd) DATE_ 
    from (SELECT 'FRI' dd from CVT_T1_DAYS where FRI = 1)
    where to_date('&amp;indate', 'mm/dd/yyyy') &lt;= sysdate
          and   next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    connect by rownum &lt;= round((sysdate - to_date('&amp;indate', 'mm/dd/yyyy'))/7) 
            and next_day(sysdate - (rownum * 7), dd) &gt;= to_date('&amp;indate', 'mm/dd/yyyy')
    order by date_;
            
    declare
    v_datechosen date      := to_date('&amp;indate', 'mm/dd/yyyy');
    v_weeksdiff  number    := round((sysdate - v_datechosen)/7);
    v_sysdate    date      := sysdate;
    
    v_dd char(5);
    v_date date;
    
    cursor dates is
            select dd, next_day(v_sysdate - (rownum * 7), dd) DATE_ 
            from (SELECT 'MON' dd from CVT_T1_DAYS where mon = 1)
            where v_datechosen &lt;= v_sysdate
            and next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            connect by rownum &lt;= v_weeksdiff and 
                       next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            union
            select dd, next_day(v_sysdate - (rownum * 7), dd) DATE_ 
            from (SELECT 'TUE' dd from CVT_T1_DAYS where tue = 1)
            where v_datechosen &lt;= v_sysdate
            and next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            connect by rownum &lt;= v_weeksdiff and 
                       next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            union
            select dd, next_day(v_sysdate - (rownum * 7), dd) DATE_ 
            from (SELECT 'WED' dd from CVT_T1_DAYS where wed = 1)
            where v_datechosen &lt;= v_sysdate
            and next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            connect by rownum &lt;= v_weeksdiff and 
                       next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            union
            select dd, next_day(v_sysdate - (rownum * 7), dd) DATE_ 
            from (SELECT 'THU' dd from CVT_T1_DAYS where thu = 1)
            where v_datechosen &lt;= v_sysdate
            and next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            connect by rownum &lt;= v_weeksdiff and 
                       next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            union
            select dd, next_day(v_sysdate - (rownum * 7), dd) DATE_ 
            from (SELECT 'FRI' dd from CVT_T1_DAYS where FRI = 1)
            where v_datechosen &lt;= v_sysdate
            and next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            connect by rownum &lt;= v_weeksdiff and 
                       next_day(v_sysdate - (rownum * 7), dd) &gt;= v_datechosen
            order by date_;
    
    begin
            dbms_output.enable(1000000);
            dbms_output.put_line(v_weeksdiff||' '||to_date('&amp;indate', 'mm/dd/yyyy'));
            
            open dates;
    
            LOOP
              FETCH dates into v_dd, v_date;
              EXIT WHEN dates%NOTFOUND;
              dbms_output.put_line(v_dd ||'          '||v_date);
            END LOOP;
            
            close dates;
    end;
    
    

  13. Bharani says:

    ans for q 8
    WITH csv AS(
    select (to_char(trunc(sysdate,’MONTH’),’MM’)-level) as Mnt from dual where (to_char(trunc(sysdate,’MONTH’),’MM’)-level) >-1 connect by level < 20 )
    select add_months(trunc(sysdate,'MONTH'),-csv.Mnt), add_months(trunc(sysdate,'MONTH'),-csv.Mnt)-1 from dual ,csv

  14. MVVSSARMA says:

    pl answer to my query, I have a table emp (empno,login)—- in my table an employee can login many times in a day. Assume each employee 4 times logged into the table with employeeno 11,22,33,44 since one week. Now I want a query to list all employees 11,22,33,44 once per day.(total I need to get 7 records for each employee)….
    please suggest the ansewr

    • Dayanandsm says:

      please try this !
      select empno,login from emp where to_Date(login) >= to_date(sysdate – 7) order by login desc;

  15. Daniel says:

    very usefull !
    I really appreciate that !

  16. Malshan says:

    Hi,

    I want to select 1st,10th and 20th of the month by giving 1,10,20 as the parameters. is there the a possible way?
    plz help

  17. Makal says:

    Thanks for sharing the above queries. very useful.
    I need one query which will give me the last month salary drawn of each employee. All employee last month salary is not same. I tried the same
    the below query works for unique record but not for the last

    select * From demo_orders a
    where order_id not IN (
    select order_id from demo_orders b
    where b.customer_id = a.customer_id and rownum=1
    );
    logically I want the

    select * From demo_orders a
    where order_id IN (
    select b.order_id from demo_orders b
    where a.customer_id = b.customer_id and rownum=1 order by a.customer_id );

  18. rk goud says:

    very usefull …… looking forward to see much stufff……………………………

  19. Pugazhendhi_r says:

    Hi can u pls share me any queries to find the table name if i know the table header. As i’m beginner unable to find it

  20. Arun says:

    Hi,

    How to find a value in a pipe delimiter value.

    For ex: Assume that we have a column A and B. In A column i have value ‘A1’ and in B column i have a value like ‘A1|B1|C1|D1’. Now i have to search A1 in B column. Please note that: A and B columns are in different table.

  21. Jo says:

    Please help me to optimize following code as it is taking a lot of time to execute

    :select distinct Cust_no_717 from (select a1.cust_no_717, a1.cust_cc_no_717, a1.cust_long_name_717 from customer a1 where a1.cust_client_717 LIKE ‘%’ UNION select a2.cust_no_717, a2.cust_cc_no_717, a2.cust_long_name_717 From Customer a2, alias_connector where ( connection_alias_778 like ‘%’ and (connection_status_778 =’BA’) and connection_cust_no_778 = a2.cust_no_717))

  22. pratik thakar says:

    kindly help me to find last one hour and previous day database increased or decreased size

  23. krishna says:

    i have tables
    CREATE TABLE Classes (
    className VARCHAR2(20),
    typeClass CHAR(2),
    country VARCHAR2(15),
    numGuns INT,
    bore INT,
    displacement INT,
    CONSTRAINT pkClasses PRIMARY KEY (className),
    CHECK (typeClass IN (‘bb’, ‘bc’))
    );

    CREATE TABLE Ships
    (
    shipName VARCHAR2(20),
    shipClass VARCHAR2(20),
    launchYr INT,
    CONSTRAINT pkShips PRIMARY KEY (shipName),
    CONSTRAINT fkClasses FOREIGN KEY (shipClass) REFERENCES Classes (className)
    );

    i want Find for each class, the year when the latest ship of that class was launched. Order the results by the name of the class.

  24. Sathishkumar says:

    I have one doubt in oracle.I sent on query.I need last one hour data on that query.

    SELECT action_view.id,
    action_view.string_value AS action,
    action_view.userid,
    user_info.email ,
    to_char(to_date(‘1970-01-01’, ‘YYYY-MM-DD’) + (action_view.audittime/ 86400000),’MM-DD-YYYY HH24:MI:SS’) as audittime
    ,
    SUBSTR(action_path.string_value,instr(action_path.string_value,’cm:’,-1)+3) AS FileName,
    action_path.string_value AS path
    FROM ALFDBSPRFSCMA.cisco_audit_entry_action_view action_view,
    ALFDBSPRFSCMA.cisco_audit_entry_path_view action_path,
    ALFDBSPRFSCMA.cisco_audit_entry_type_view type_view,
    ALFDBSPRFSCMA.cisco_view_user_info user_info
    WHERE action_view.id =action_path.id
    AND action_view.id =type_view.id
    AND action_view.userid=user_info.user_id
    AND action_path.string_value LIKE (‘/app:company_home/st:sites/cm:nextgen-edcs/cm:documentLibrary/%’)
    AND action_view.userid != ‘admin’
    AND type_view.string_value =’cs:ciscodoc’
    AND action_view.string_value != ‘READ’
    AND action_view.audittime

    We are showing audit time format like mentioned in green color. The yellow color condition should be last one hour from sys time.

    Eg:

    action_view.audittime > ((sysdate – to_date(’01-JAN-1970′,’DD-MON-YYYY’))-5) * (86400000)+to_number(to_char(systimestamp,’FF3′)) but this is not working properly.

  25. Anuj says:

    Very nice work. Thanks a lot…
    Well can you please have a look on 7th query. I think we need to add to_date function to months_between function.

  26. thiru says:

    please give me a clarification on this;
    if we give startup command when instance is in idle condition, what happens to database. please provide me answer urgent

  27. mdivya says:

    meaning of queries

  28. Richard says:

    I am looking to show the remaining Monday’s in a year and I have the following SQL which shows all the Mondays in a year. How can I change it to only show the remaining Mondays? TIA

    SELECT TRUNC (SYSDATE, ‘YEAR’) + LEVEL – 1 the_date from dual
    WHERE TO_CHAR (TRUNC (SYSDATE, ‘YEAR’) + LEVEL – 1, ‘Dy’) IN (‘Mon’)
    CONNECT BY LEVEL <= LAST_DAY (SYSDATE) – TRUNC (SYSDATE, 'YEAR') + 1;

  29. Suresh Dongare says:

    Hello Viral,
    I just vist your side i realy like this queries ..losts of thanks for shaering this like queries .

  30. Suresh Dongare says:

    How convert latter one into 1 in oracle without using any Comparision condations
    i.e case ,decode.

  31. harish besant says:

    Hi, thanks for share the information with us.. keep update your blogs.

  32. Soumya says:

    Very useful…Thank u so much.

  33. Soumya says:

    Please give me a query to find
    1. how long the database or application has used in a particular day.
    2. Most visited pages in the application.

  34. sai says:

    Hello guys please tell me the query to get the output like the below:
    AaBbCcDd

  35. praveeen says:

    Valuable information thanks for sharing

  36. jjjjj says:

    Create a query that displays the employees’ names, job and hire date also display a column with the name “new hire date” in which increase 6 months in the hire date of salesman , 2 months in the hire date of clerk, 1 months in the hire date of president

  37. virendra says:

    hi

    anyone help me to write a query to find data fro 1st to last of the month. like
    01-Jan-2016
    02-Jan-2016
    03-Jan-2016
    04-Jan-2016
    .
    .
    .
    .
    .
    30-Jan-2016

    from dual table

    • radhiya says:

      SELECT TRUNC(SYSDATE, ‘MM’) + LEVEL – 1 AS day
      FROM dual
      CONNECT BY TRUNC(TRUNC(SYSDATE, ‘MM’) + LEVEL – 1, ‘MM’) = TRUNC(SYSDATE, ‘MM’)
      ;

  38. rakesh says:

    Thanks a million buddy. its very helpfull.

  39. Ramanareddy G says:

    Awesome Stuff Viral Patel. Simply Superb.Thanks a lottttttt

  40. Aravind says:

    Great man..

    Let you have a bright future ahead

  41. Sun Oracle Servers Houston says:

    Hi, Thanks for sharing the information. Reading this article gave me many things to think about.

  42. anonymous says:

    Good one

  43. Maciej Soltysiak says:

    Query #30 is missing a match on username. Please add
    AND A.username = b.username so that you don’t get colliding SIDs of different users.

  44. Dinesh Krishnan says:

    Very useful one

  45. sairam says:

    Hi,
    i have the db capacity script but it has to execute on the last date of every month

    is there is any automatic script,

    thanks in advance

  46. mimi says:

    can someone help me how to do query for insert,delete,select, and update table?

  47. S dhara says:

    Want to write a procedure count the words in a given string

  48. mamatha says:

    very useful

  49. =query(‘New Birthdays’!A1:B,A1,1)

    need help to keep birthdates in excel

  50. Prachi Digraskar says:

    Can anyone tell me how to display count of day wise total employees where day should start from Monday

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