Friday, 27 April 2018

e.g. truncate table cascade

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Preparation of Test Data test=#  create table employees (id integer, name varchar, department_id integer); test=#  create table departm...
Thursday, 26 April 2018

e.g. fetching JSON data

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Preparation of Test Data test=#  create table  T_JSON_DATA  (id INTEGER, body JSON); test=# insert into T_JSON_DATA values (1, '{ ...
Wednesday, 25 April 2018

ORA-02292 solution

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Preparation -- Insert test data into DEPARTMENT and EMPLOYEES tables. SQL> INSERT INTO DEPARTMENTS VALUES ( 280 ,'New Department...
Thursday, 19 April 2018

e.g. count and distinct aggregate functions

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examples; count (1) - count(*) - count(column_name) - count( distinct (column_name)) e.g. count aggregate function SQL> SELECT     ...
Wednesday, 11 April 2018

ORA-02449 solution

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Preparation SQL> CREATE TABLESPACE EXAMPLE_TS DATAFILE   'C:\ORACLEXE_XE\APP\ORACLE\ORADATA\XE\example_01.dbf' SIZE 512K REUSE...

ORA-01549 solution

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Preparation SQL> CREATE TABLESPACE EXAMPLE_TS DATAFILE   'C:\ORACLE_XE\APP\ORACLE\ORADATA\XE\example_01.dbf' SIZE 512K REUSE ...
Monday, 9 April 2018

e.g. pivot clause

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Preparation  * Define column names for pivot table SQL> SELECT LISTAGG (           '''' || JOB_ID || '''...
Friday, 6 April 2018

How to use SPOOL command in Oracle?

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WINDOWS e.g. SQL>  sqlplus / as sysdba; SQL> SET LINESIZE 200; SET PAGESIZE 100; -- define a output file for writing SPOOL ...
Tuesday, 3 April 2018

What are pencil hardness grading scales?

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2H -> H -> F -> HB -> B -> 2B H means Hard (hard-tipped) B means Bold  (soft-tipped) F means Fine Info: from left to r...
Friday, 30 March 2018

What is implicit commit?

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After every DDL operation, implicit commit occurs such as while defining a new table. e.g. CREATE TABLE HR.EXAMPLE(ABC char(1)); Also w...

blob vs bfile data types

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BLOB (binary large objects) stores unstructured binary large objects. It is often used for graphic images, video clips, and sounds. The BLO...

How to do CTAS in Oracle?

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CTAS stands for Create Table As Select e.g. SQL> CREATE TABLE HR.EMPLOYEES_NEW AS     SELECT * FROM HR.EMPLOYEES; -> By defau...

NULLS LAST keyword usage

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-> HR.EMPLOYEES will be test table. SQL>  DESC HR.EMPLOYEES; e.g. To populate all data SQL>  SELECT * FROM HR.EMPLOYEES; T...

ORA-01495 solution

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Action SQL> ANALYZE TABLE HR.EMPLOYEES LIST CHAINED ROWS INTO CHAINED_ROWS ; Error ORA-01495 : specified chain row table not found ...
Friday, 23 March 2018

ORA-02270 solution

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Preparation SQL> create table A (id number, soid number); SQL> create table B (id number); Action SQL>  alter table A add...
Friday, 16 March 2018

ORA-00959 solution

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Action SQL>  CREATE TABLE HR.EXAMPLE(ABC char(1)); Error ORA-00959: tablespace '_$deleted$40$0' does not exist Reason Def...
Friday, 9 March 2018

ORA-02449 solution

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Preparation SQL> -- A table is child table create table A (id number, soid number); SQL> -- B table is parent table create tab...
Friday, 2 March 2018

ORA-01720 solution

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Preparation " employees " table exists in HR schema " v_employees " view exists in HR2 schema; SQL> grant select ...
Friday, 23 February 2018

How to use SQL Tuning Advisor in Oracle SQL Developer?

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Oracle SQL Developer -> Connections -> Right mouse click on desired database connection name (e.g. XE) -> Click "Open SQL Wo...

How to take screenshot on top window quickly?

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e.g. Alt key + Print Screen  key -> Then CTRL + V in "mspaint.exe" -> Save it.