I have a stored procedure where i need to pass a string to use in the query.
Stored procedure example:
BEGIN
SET #query = query;
SELECT * FROM test WHERE #query
END
How I would like to call it with a string:
CALL proceduretet('activity_id = 1 OR activity_id = 2')
The query can be different each time, sometimes there will be 1 activity_id and sometimes 4 or more.
I have tried to pass it as a varchar and text, but it won't work.
So is there a way to pass a string to stored procedures and use it in the query?
Regards, Andreas
The code would look like:
BEGIN
SET #query = query;
SET #sql = concat('SELECT * FROM TEST WHERE ', #query);
PREPARE stmt from #sql;
EXECUTE stmt;
END;
Related
CREATE DEFINER=`root`#`localhost` PROCEDURE `get_plan_images`(
_list varchar(2000)
)
BEGIN
SET #LIST=_list;
set #sql = concat('SELECT plan_id, plan_image
FROM ibuild.plan_images
where plan_id in (', #LIST , ')');
PREPARE q FROM #sql;
execute q;
END
What does concat do here? And what does this statement means PREPARE q FROM #sql;
CONCAT simply merges two or more pieces of text together. In the example above, #LIST contains a list of ids passed in to the procedure. After the CONCAT, #sql becomes a string that contains something like:SELECT plan_id, plan_image FROM ibuild.plan_images where plan_id in (1,2,3)
See here: MySQL CONCAT Function
The PREPARE statement just gives the statement a name so you can execute it. See here: MySQL PREPARE
I´m trying to define a stored procedures which accepts 2 parameteres , one would be the table column which has to be equal with the second parameter i will provide.
Code :
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `selectUserByField`(IN _field varchar(150) , IN _value varchar(150))
BEGIN
SET #sql = CONCAT('SELECT * FROM Users WHERE', _field, '=' ,_value);
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END
The thing is that i don´t know how to provide the _value param as a string. If i run it like this i get a Mysql 1064 near ´=myEmail´( params where ´userEmail´,´myEmail´). Thanks !
In your below code, you are missing a space after WHERE. It should be like below; give a space after WHERE and in =
SET #sql = CONCAT('SELECT * FROM Users WHERE ', _field, ' = ' ,_value);
i have tried to create MySQL store procedure in that i want to make dynamic query.
code on which i working..
DELIMITER $$
DROP PROCEDURE IF EXISTS `test`.`selectp` $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `selectp`(in a_str_Condition varchar(500))
BEGIN
SET #Query = 'SELECT * from test123';
IF a_str_Condition != ''
THEN
SET #strCondition = CONCAT(' WHERE ? ');
SET #param = a_str_Condition;
ELSE
SET #strCondition = ' Order by aaa desc';
END IF
SET #Query = CONCAT(#Query, #strCondition );
PREPARE stmt FROM #Query;
EXECUTE stmt USING #param;
DEALLOCATE PREPARE stmt;
END $$
DELIMITER ;
here i want pass parameter as aaa = 3 and concat it with mysql query, but it show me error as below.
please let me clear on this store procedure. Any help will be Appreciate.
Trying to answer to your ...what is wrong with MySQL select Store Procedure..?
As others mentioned you have ; missing. That only solves a syntax error.
But you have bigger problems with the way you try to construct your query and EXECUTE it:
You're incorrectly trying to treat all where conditions as one parameter with WHERE ?, instead of parameterizing values like WHERE id = ?
In case you don't pass a condition you can't use USING in EXECUTE. It'll fail.
Now since you don't execute your query multiple times, you pass conditions as a string anyway, and it seems that you're more after flexibility than security, IMHO there is no much sense in using parameters here.
That being said a more succinct version of your SP might look like this
DELIMITER $$
CREATE PROCEDURE selectp(IN _conditions VARCHAR(500), IN _orderby VARCHAR(500))
BEGIN
SET #sql = CONCAT(
'SELECT * FROM test123 WHERE 1 = 1',
COALESCE(CONCAT(' AND ', NULLIF(_conditions, '')), ''),
' ORDER BY ',
COALESCE(NULLIF(_orderby, ''), 'id DESC')
);
PREPARE stmt FROM #sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END$$
DELIMITER ;
Usage examples:
-- default parameters either with null or an empty string
CALL selectp('', '');
CALL selectp(NULL, NULL);
-- set where conditions
CALL selectp('id IN(1, 3)', NULL);
-- set order by
CALL selectp(NULL, 'col1 DESC, col2');
Here is SQLFiddle demo
You've lost a semicolon after END IF.
And that's what mysql is pointed you to - it always shows you the expression part it couldn't parse. So always look at the code right before the one from the error description.
There should be a semi column after the END IF statement:
ELSE
SET #strCondition = ' Order by aaa desc';
END IF; //add semicolumn here
Before this line:
SET #Query = CONCAT(#Query, #strCondition );
How do I cache dynamic query from store procedure?
Right now I have created my store procedure like this :
CREATE PROCEDURE usp_MyProcedure (
IN UserID INT,
....
)
BEGIN
SET #sqlQuery = CONCAT("SELECT Name From Users WHERE UserID > ", UserID, " AND UserID IN ( SELECT UserID FROM OtherTable WHERE UserID = ", UserID, " ) Order by Name")
PREPARE stmt FROM #sqlQuery;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END;
But this kind of query does not cached. so, every time it gets more time to execute/process query.
Now I have tried some other method like this:
CREATE PROCEDURE usp_MyProcedure (
IN UserID INT,
....
)
BEGIN
SET #UserID = UserID;
SET #sqlQuery = "SELECT Name From Users WHERE UserID > ? AND UserID IN ( SELECT UserID FROM OtherTable WHERE UserID = ? ) Order by Name";
PREPARE stmt FROM #sqlQuery;
EXECUTE stmt #UserID, #UserID; -- here i passed same variable twice.
DEALLOCATE PREPARE stmt;
END;
In the above case I have to pass same variable (#UserID) twice, because it is used 2 times in my query. but this job is very hectic in long or complex query. so, how do I avoid this?
One another method I tried as follows:
CREATE PROCEDURE usp_MyProcedure (
IN UserID INT,
....
)
BEGIN
SET #UserID = UserID;
SET #sqlQuery = "SELECT Name From Users WHERE UserID > #UserID AND UserID IN ( SELECT UserID FROM OtherTable WHERE UserID = #UserID ) Order by Name";
PREPARE stmt FROM #sqlQuery;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END;
But above query again does not cached. so, execution time is very long. and this type of variable declared as session global variable has may be conflict with another store procedure's variable. because I have call store procedure within this store procedure and variable name should be same in another store procedure.
So, let me know what is the best solution for the same.
Thanks.
Sorry just posted a mistaken one,
DELIMITER //
CREATE PROCEDURE yourprocedurenamehere(IN state CHAR(2))
BEGIN
SET #mystate = state;
SET #sql = CONCAT('SELECT * FROM BLABLABLA WHERE BLA = ?');
PREPARE stmt FROM #sql;
EXECUTE stmt USING #mystate;
END;
//
Sorry pal, just edited my code hahaha I got this wrong
A short answer is that there is no way to do it. In theory, you could identify prepared statement name with sha1(prepared statement query text), and use this as a statement handle. But there is no way to dynamically execute a statement which name is stored in a variable or in a table: EXECUTE itself is not allowed in Dynamic SQL query text.
A different question is whether you need a Dynamic SQL in your example at all, it seems like a standard SQL stored procedure parameterized with input parameters could do just fine.
I'm trying to pass a table name into my mysql stored procedure to use this sproc to select off of different tables but it's not working...
this is what I"m trying:
CREATE PROCEDURE `usp_SelectFromTables`(
IN TableName varchar(100)
)
BEGIN
SELECT * FROM #TableName;
END
I've also tried it w/o the # sign and that just tells me that TableName doesn't exist...which I know :)
SET #cname:='jello';
SET #vname:='dwb';
SET #sql_text = concat('select concept_id,concept_name,',#vname,' from enc2.concept a JOIN enc2.ratings b USING(concept_id) where concept_name like (''%',#cname,'%'') and 3 is not null order by 3 asc');
PREPARE stmt FROM #sql_text;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
An extra bit that caused me problems.
I wanted to set the table name and field dynamically in a query as #kyle asked, but I also wanted to store the result of that query into a variable #a within the query.
Instead of putting the variable #a into the concat literally, you need to include it as part of the string text.
delimiter //
CREATE PROCEDURE removeProcessed(table_name VARCHAR(255), keyField VARCHAR(255), maxId INT, num_rows INT)
BEGIN
SET #table_name = table_name;
SET #keyField = keyField;
SET #maxId = maxId;
SET #num_rows = num_rows;
SET #sql_text1 = concat('SELECT MIN(',#keyField,') INTO #a FROM ',#table_name);
PREPARE stmt1 FROM #sql_text1;
EXECUTE stmt1;
DEALLOCATE PREPARE stmt1;
loop_label: LOOP
SET #sql_text2 = concat('SELECT ',#keyField,' INTO #z FROM ',#table_name,' WHERE ',#keyField,' >= ',#a,' ORDER BY ',#keyField,' LIMIT ',#num_rows,',1');
PREPARE stmt2 FROM #sql_text2;
EXECUTE stmt2;
DEALLOCATE PREPARE stmt2;
...Additional looping code...
END LOOP;
END
//
delimiter ;
So in #sql_text1 assign the result of the query to #a within the string using:
') INTO #a FROM '
Then in #sql_text2 use #a as an actual variable:
,' WHERE ',#keyField,' >= ',#a,' ORDER BY '
It depends on the DBMS, but the notation usually requires Dynamic SQL, and runs into the problem that the return values from the function depend on the inputs when it is executed. This gives the system conniptions. As a general rule (and therefore probably subject to exceptions), DBMS do not allow you to use placeholders (parameters) for structural elements of a query such as table names or column names; they only allow you to specify values such as column values.
Some DBMS do have stored procedure support that will allow you to build up an SQL string and then work with that, using 'prepare' or 'execute immediate' or similar operations. Note, however, that you are suddenly vulnerable to SQL injection attacks - someone who can execute your procedure is then able to control, in part, what SQL gets executed.