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Renaming the columns and calculations in the result set page 3

MySQL

The query

  1. SELECT 'SELECT' "SELECT"
will give us upon execution

SELECTSELECT

I can explain this behaviour by default settings which adopt usage of double quote symbol (") in the same manner as single quote (') - for delimiting the character constant. So two string unites into one string. However if you type the query as

  1. SELECT 'SELECT' AS "SELECT";
or as

  1. SELECT 'SELECT' `SELECT`;
you'll obtain desired result.

To forbid usage of double quote as single quote, you can replace settings by standard ones. The following statement changes the setting mentioned above:

  1. SET GLOBAL sql_mode='ANSI_QUOTES';
but this one makes all the settings as standard ones:

  1. SET GLOBAL sql_mode='ANSI';

After that the query

  1. SELECT 'SELECT' "SELECT";
will give us

SELECT
SELECT

Oracle & PostgreSQL

These DBMS behave in standard manner. Note only that Oracle (in view of FROM clause is mandatory)  demands to rewrite our query as

  1. SELECT 'SELECT' "SELECT" FROM dual;


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