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I have a mysql stored procedure from this (google book), and one example is this:
DELIMITER $$ DROP PROCEDURE IF EXISTS my_sqrt$$ CREATE PROCEDURE my_sqrt(input_number INT, OUT out_number FLOAT) BEGIN SET out_number=SQRT(input_number); END$$ DELIMITER ; The procedure compiles fine. (I am using MySQL Query Browser in ubuntu).
However when I call the procedure:
CALL my_sqrt(4,@out_value); (also in query browser)
It returns an error:
(1064) check the manual that correspond to the... Why isn't this example working?
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A Stored Procedure can have any number of output parameters. The simple logic is this — If you want to return 1 value then use 1 output parameter, for returning 5 values use 5 output parameters, for 10 use 10, and so on.
An input/output parameter is a parameter that functions as an IN or an OUT parameter or both. The value of the IN/OUT parameter is passed into the stored procedure/function and a new value can be assigned to the parameter and passed out of the module. An IN/OUT parameter must be a variable, not a constant.
The MySQL Stored procedure parameter has three modes: IN, OUT, and INOUT. When we declare an IN type parameter, the application must pass an argument to the stored procedure. It is a default mode. The OUT type parameter, the stored procedure returns a final output generated by SQL Statements.
By using IN OUT parameter we can pass values into a parameter and return a value to the calling program using the same parameter. But this is possible only if the value passed to the procedure and output value have a same datatype. This parameter is used if the value of the parameter will be changed in the procedure.
Unable to replicate. It worked fine for me:
mysql> CALL my_sqrt(4, @out_value); Query OK, 0 rows affected (0.00 sec) mysql> SELECT @out_value; +------------+ | @out_value | +------------+ | 2 | +------------+ 1 row in set (0.00 sec) Perhaps you should paste the entire error message instead of summarizing it.
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