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Create a temporary table in a SELECT statement without a separate CREATE TABLE

开发者 https://www.devze.com 2023-03-01 22:04 出处:网络
Is it possible to create a temporary (session only) table from a select st开发者_开发百科atement without using a create table statement and specifying each column type? I know derived tables are capab

Is it possible to create a temporary (session only) table from a select st开发者_开发百科atement without using a create table statement and specifying each column type? I know derived tables are capable of this, but those are super-temporary (statement-only) and I want to re-use.

It would save time if I did not have to write up a create table command and keep the column list and type list matched up.


CREATE TEMPORARY TABLE IF NOT EXISTS table2 AS (SELECT * FROM table1)

From the manual found at http://dev.mysql.com/doc/refman/5.7/en/create-table.html

You can use the TEMPORARY keyword when creating a table. A TEMPORARY table is visible only to the current session, and is dropped automatically when the session is closed. This means that two different sessions can use the same temporary table name without conflicting with each other or with an existing non-TEMPORARY table of the same name. (The existing table is hidden until the temporary table is dropped.) To create temporary tables, you must have the CREATE TEMPORARY TABLES privilege.


In addition to psparrow's answer if you need to add an index to your temporary table do:

CREATE TEMPORARY TABLE IF NOT EXISTS 
  temp_table ( INDEX(col_2) ) 
ENGINE=MyISAM 
AS (
  SELECT col_1, coll_2, coll_3
  FROM mytable
)

It also works with PRIMARY KEY


Use this syntax:

CREATE TEMPORARY TABLE t1 (select * from t2);


Engine must be before select:

CREATE TEMPORARY TABLE temp1 ENGINE=MEMORY 
as (select * from table1)


ENGINE=MEMORY is not supported when table contains BLOB/TEXT columns


As I understand it, a SELECT statement will work on the temporary table if you're using it in something like phpMyAdmin, but following that SELECT, the temporary table will be gone. This means set up exactly what you want to do with it first, and don't view any results till your 'action' statements that change the data (DELETE, UPDATE) are complete.

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