List temporary table columns in mysql - mysql

Question

I have created one temporary table named "table1". I am trying to list the columns of my temp table. I am not getting any values. Here is my mysql query.
SELECT column_name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'table2';
Any body help me please?
Thanks

Answer 1

You cannot get the temporary table columns using the INFORMATION_SCHEMA
The only way which you can use is to go with SHOW CREATE TABLE table2
"INFORMATION_SCHEMA.COLUMNS" does not contains columns of temporary table.

Answer 2

You can use SHOW COLUMS to achieve this.
Example Table:
CREATE TEMPORARY TABLE SalesSummary (
product_name VARCHAR(50) NOT NULL,
total_sales DECIMAL(12,2) NOT NULL DEFAULT 0.00,
avg_unit_price DECIMAL(7,2) NOT NULL DEFAULT 0.00,
total_units_sold INT UNSIGNED NOT NULL DEFAULT 0
);
Command:
SHOW COLUMNS FROM SalesSummary;
Outout:
mysql> SHOW COLUMNS FROM SalesSummary;
+------------------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------------+------------------+------+-----+---------+-------+
| product_name | varchar(50) | NO | | NULL | |
| total_sales | decimal(12,2) | NO | | 0.00 | |
| avg_unit_price | decimal(7,2) | NO | | 0.00 | |
| total_units_sold | int(10) unsigned | NO | | 0 | |
+------------------+------------------+------+-----+---------+-------+
4 rows in set (0.00 sec)
More details are in the manual Section 13.7.5.5 for MySQL 5.7. Link
Another possibility is using SHOW CREATE TABLE:
mysql> SHOW CREATE TABLE SalesSummary\G
*************************** 1. row ***************************
Table: SalesSummary
Create Table: CREATE TEMPORARY TABLE `SalesSummary` (
`product_name` varchar(50) NOT NULL,
`total_sales` decimal(12,2) NOT NULL DEFAULT '0.00',
`avg_unit_price` decimal(7,2) NOT NULL DEFAULT '0.00',
`total_units_sold` int(10) unsigned NOT NULL DEFAULT '0'
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)
Here are some more details.
In Mysql 5.7 there is a seperate table called INNODB_TEMP_TABLE_INFO to achieve this.

Answer 3

It is possible to get a list of column names for any table.
This method will also work for TEMPORARY tables:
SET #columns_string = ''
;
SHOW
COLUMNS
FROM
`mysql`.`user`
WHERE
#columns_string := CONCAT(`Field`, ',', #columns_string)
;
SELECT #columns_string
;
#columns_string will have a value of:
account_locked,password_lifetime,password_last_changed,password_expired,authentication_string,plugin,max_user_connections,max_connections,max_updates,max_questions,x509_subject,x509_issuer,ssl_cipher,ssl_type,Create_tablespace_priv,Trigger_priv,Event_priv,Create_user_priv,Alter_routine_priv,Create_routine_priv,Show_view_priv,Create_view_priv,Repl_client_priv,Repl_slave_priv,Execute_priv,Lock_tables_priv,Create_tmp_table_priv,Super_priv,Show_db_priv,Alter_priv,Index_priv,References_priv,Grant_priv,File_priv,Process_priv,Shutdown_priv,Reload_priv,Drop_priv,Create_priv,Delete_priv,Update_priv,Insert_priv,Select_priv,User,Host,
The problem with this solution (besides needing to parse a string) is that the SHOW COLUMNS command will always generate an (empty) resultset.
This means that you can't really use this method in a stored procedure that returns a SELECT (you will end up with more than one resultset).