如何在mysql过程中创建临时表并生成不同的名称？

Question

I want to create temp tables which have different table names.

The stored procedure takes no input arguments, create a temp table and return a table name of the table as T_1, T_2, T_3....

How can I implement this in mysql stored procedure?

Answer 1

Following procedure should help you. But this kind of sequence generation will work in current connection session only. But I hope it is OK as you are expecting it on temporary tables .

delimiter //

drop procedure if exists set_new_temp_table //

create procedure set_new_temp_table()
begin
  if( @temp_table_seq_num is null ) then 
    set @temp_table_seq_num := 1;
  end if;

  set @temp_table_name := Concat( 'T_', @temp_table_seq_num );

  set @sql := concat( 'create temporary table if not exists '
                      , @temp_table_name 
                      , '( col1 int, col2 varchar(10) )'
                    );

  prepare stmt from @sql;
  execute stmt;
  drop prepare stmt;

  set @temp_table_seq_num := ( cast( @temp_table_seq_num as decimal ) + 1 );
  set @sql := null;
end;
//

delimiter ;

select @temp_table_name; -- should return a NULL before first ever call to SP
call set_new_temp_table(); select @temp_table_name;

Demo @ MySQL 5.5.32 Fiddle

Answer 2

This is full example

SELECT UUID() INTO @RandomName;
SET @TempTableNameWithSpecialCharectors := CONCAT('TEMP', @RandomName);
SET @TempTableName := REPLACE(@TempTableNameWithSpecialCharectors, '-', '');
SET @tempTable := CONCAT('CREATE TEMPORARY TABLE IF NOT EXISTS ', @TempTableName, ' (InteractionRequestId bigint(20), SendCount int)');

-- SELECT @tempTable;
PREPARE createStmt FROM @tempTable;
EXECUTE createStmt;
DROP PREPARE createStmt;


SET @enqueueDate := '2017-05-28';
SET @insertIntoTable := CONCAT('
INSERT INTO ', @TempTableName, '(InteractionRequestId, SendCount) SELECT InReq.Id, COUNT(*) AS SendCount FROM InteractionRequests AS InReq INNER JOIN InteractionResponses InRes ON InReq.Id = InRes.InteractionRequestId
WHERE InReq.EnqueuedRequest > "', @enqueueDate, 
'" GROUP BY InReq.Id');

SELECT @insertIntoTable;
PREPARE insertStmt FROM @insertIntoTable;
EXECUTE insertStmt;
DROP PREPARE insertStmt;

SET @SelctResult := CONCAT('SELECT * FROM ', @TempTableName);
PREPARE selectStmt FROM @SelctResult;
EXECUTE selectStmt;
DROP PREPARE selectStmt;

Answer 3

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.