Question

Am using MySQL 5 on OS X – Snow Leopard…

Have working code in place which obtains the highest sequence number ID from a sequence table and then increments and assigns it to its corresponding table:

The original code’s purpose is to dynamically increments a specific table’s last sequence id and set its corresponding table’s id to that new value.

Notes:

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1. Original Code Snippet (which is working):

Get last sequence number

replace into my_sequence_id_s set id = 
(select max(CONVERT(sequence_id, signed)) from my_table_t);

Increments the number

insert into my_sequence_id_s set id = null;

Saves the number as a variable

set @dynamicId = last_insert_id();

Print

select @dynamicId;

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2. Refactoring:

DROP PROCEDURE IF EXISTS generate_dynamic_id#

CREATE PROCEDURE generate_dynamic_id

(IN _sequence_table varchar(40),
 IN _actual_table varchar(40), 
 IN _id_field VARCHAR(40), 
 OUT dynamic_id varchar(40))

 BEGIN
  -- Get Last Sequence Number
     set @getLastSequenceNumberSQL = 
     concat('REPLACE INTO ', _sequence_table, 'SET ID = 
     (select max(CONVERT(',_id_field,', signed)) 
      from ', _actual_table, ');');
      prepare lastRecordStmt from @getLastSequenceNumberSQL;
      execute lastRecordStmt;
      deallocate prepare lastRecordStmt;

  -- Increments the number.
      set @createNewSequenceNumberSQL = 
      concat('insert into ', _sequence_table ,' set id = null;');
      prepare newSequenceNumberStmt from @createNewSequenceNumberSQL;
      execute newSequenceNumberStmt;
      deallocate prepare newSequenceNumberStmt;

   -- Set the number as a dynamic variable.
      set @dynamic_id = last_insert_id();
END;
#

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3. Here’s the calling function (which fails):

— Get dynamically incremented id

call generate_dynamic_id(
   'my_sequence_id_s', 'my_table_t', 'table_id', @dynamicId);

Error:

com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: 

You have an error in your SQL syntax; 

check the manual that corresponds to your MySQL server version

for the right syntax to use near

'ID = (select max(CONVERT(id_field, signed)) from my_table_t)' at line 1

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For some odd reason, dynamic function calls are not allowed in Stored Functions or Triggers, so that’s why a Stored Procedure was used.

As you can see, I am setting up varchars at the parameters and then trying to concatenate them as strings and run them inside prepared statements.

Any help would be greatly appreciated…

Answer 1

concat(‘REPLACE INTO ‘, _sequence_table, ‘SET ID =

where space between _sequence_table and SET ID?