copying data from one column to another with sql

2019-03-08

~2 min read

214 words

If you need to copy all data from one column to another column in SQL, use the UPDATE method.

If it’s a simple copy for copy, without conditionals, across tables, etc., the query is simply:

UPDATE `table_name` SET
 `destination_column` = `source_column`

The full set of options :

[ WITH [ RECURSIVE ] with_query [, …] ]
UPDATE [ ONLY ] table_name [ * ] [ [ AS ] alias ]
    SET { column_name = { expression | DEFAULT } |
          ( column_name [, …] ) = [ ROW ] ( { expression | DEFAULT } [, …] ) |
          ( column_name [, …] ) = ( sub-SELECT )
        } [, …]
    [ FROM from_list ]
    [ WHERE condition | WHERE CURRENT OF cursor_name ]
    [ RETURNING * | output_expression [ [ AS ] output_name ] [, …] ]

Full documentation on UPDATE in Postgres for the current version (11), is here: PostgreSQL: Documentation: 11: UPDATE

For more discussions, see StackOverflow:

Postgres discussion: How can I copy data from one column to another in the same table
MySQL discussion: mysql - Copy values from one column to another in the same table - Stack Overflow

Turns out that at least in the simplest case, Postgres and MySQL are identical.

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