I am trying to use the result of a query as a table.
This query works fine:
SELECT date, number FROM `table_A`
The query below as well --> its result is table_B as a string of character not the table itself
SELECT nametable FROM `list_repository` WHERE id=1
But the combined one does not:
SELECT date, number FROM (SELECT nametable FROM `list_repository` WHERE id=1) A
I expect the resulting query to be
SELECT date, number FROM `table_B`
I tried to set a variable but it does not work either:
DECLARE x VARCHAR(150) ;
SET table=( SELECT `nametable` FROM `list_repository` WHERE id=1);
SELECT * from `table`. But it would not work
Thank you for your help!
Identifiers (db, table, column names etc) in SQL are static. Therefore you can't populate them at run-time. But you can build a query as a string and execute it via dynamic SQL. Something along the lines of
SET #sql = NULL;
SELECT CONCAT("SELECT * FROM ", nametable)
INTO #sql
FROM list_repository
WHERE id = 1;
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
An example of wrapping it up into a stored procedure
DELIMITER //
CREATE PROCEDURE sp1 (IN id INT)
BEGIN
SET #sql = NULL;
SELECT CONCAT("SELECT * FROM ", nametable)
INTO #sql
FROM list_repository
WHERE id = id;
SELECT #sql;
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END//
And then invoking it
CALL sp1(1);
I've looked through a lot of posts on this site and others and I can't figure this out. I'm trying to select a list of columns from a table and then use them in a query similar to this:
set #cols = (select group_concat(column_name) as 'col_list' FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE (`TABLE_SCHEMA` = 'REPORTS' AND `TABLE_NAME` = 't_labor' AND column_name like '%host%'));
set #s = 'select ' + #cols + ' from REPORTS.t_labor';
prepare stmt from #s;
execute stmt;
deallocate prepare stmt;
-- execute ('select ' + #cols + ' from REPORTS.t_sales');
I am trying to run the above statements as-is. I also tried creating a stored procedure, but I have never worked with stored procedures in MySQL before and I don't know how to debug them. I would prefer to do this without using a stored procedure if possible, but if it's necessary that's ok.
I tried using the prepare statement, and I tried the execute statement but I couldn't get either to work.
Wild guess here, but try this.
set #cols = (select group_concat(column_name) as 'col_list' FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE (`TABLE_SCHEMA` = 'REPORTS' AND `TABLE_NAME` = 't_labor' AND column_name like '%host%'));
PREPARE stmt1 FROM 'select ? from REPORTS.t_labor';
EXECUTE stmt1 USING #cols;
DEALLOCATE PREPARE stmt1;
Finally figured it out:
set #cols = (select group_concat(column_name) as 'col_list' FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE (`TABLE_SCHEMA` = 'REPORTS' AND `TABLE_NAME` = 't_labor' AND column_name like '%host%'));
set #qry = concat('select ', #cols, ' from REPORTS.t_labor');
PREPARE stmt1 FROM #qry;
EXECUTE stmt1;
DEALLOCATE PREPARE stmt1;
Had to piece together replies from at least 5 different posts similar to this question plus Dr OSWaldo's reply.
Here is the simplified query that doesn't work.
SET #abc = CONCAT('%','string','%');
SET #query = CONCAT('SELECT *
FROM table
WHERE column LIKE ',#abc);
PREPARE stmt FROM #query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
I need to use CONCAT with SELECT because there lots of other variables in real query.
Real query works fine when I use some simple COLUMN=xyz in WHERE clause. But nothing works when I try to use LIKE %xyz%...
Use it like this
SET #abc = CONCAT('"%','string','%"');
SET #query = CONCAT('SELECT *
FROM table
WHERE column LIKE ',#abc);
PREPARE stmt FROM #query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
Check the first line I have added " to show #abc like "%string%"
can i somehow set parameter for name of table in query without using a prepare statement?
This is example:
SET #tableName = 'Customer';
SELECT * FROM #tableName;
Thanks
Depending on the version of MySQL you are using, you may be able to use something like:
SET #tableName = 'Customer';
SET #s = CONCAT('SELECT * FROM ', #tableName);
PREPARE stmt FROM #s;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
I have an stored procedure like this:
SET #query = CONCAT('insert into tblcommodity (id , idname , count)values (',p1, p2,p3,')');
PREPARE stmt FROM #query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
But when I want to run it, it has this error:
> Procedure execution failed 1136 - Column count doesn't match value
> count at row 1
and another thing is that when I just run the insert code it runs!
plz help me.
With all due respect, the way you do it kindof defeats the whole purpose of prepared statements. I'd use this form instead:
SET #query = 'INSERT INTO tblcommodity (id, idname, count) VALUES (?, ?, ?)';
PREPARE stmt FROM #query;
EXECUTE stmt USING #p1, #p2, #p3;
It should be
SET #query = CONCAT('insert into tblcommodity (id , idname , count)values (',',',p1,',', p2,',',p3,')');
Try this:
SET #query = CONCAT("insert into tblcommodity (id , idname , count) values (", p1, ", '", p2,"',",p3,")");
PREPARE stmt FROM #query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
BTW, Your code:
SET #query = CONCAT('insert into tblcommodity (id , idname , count)values (',p1, p2,p3,')');
has an starting comma:
,p1,p2,p3
it means FOUR fields in the statement.
Thats why you get an "Column count doesn't match value"