Procedures

What is a Stored Procedure?

A stored procedure is SQL code that can be accessed using SQL CALL syntax. Much like a function in other programming languages, you can pass values into a stored procedures. Results are returned as a table.

Database users create procedures. Procedures are schema and are stored along with other schema elements in the database.

How to use Stored Procedures

Stored Procedures are used to store code you want the database to execute when a user asks. In Dolt, we use built in stored procedures to allow users to do version control write operations, like create a commit.

Difference between MySQL Stored Procedures and Dolt Stored Procedures

Dolt stored procedures match MySQL stored procedures exactly.

Dolt exposes custom stored procedures for version control operations. These are named after the corresponding Dolt commands.

Interaction with Dolt Version Control

Procedures are versioned in the dolt_procedures table. You add and commit that table just like any other changed table after you create or modify a trigger.

Example

mysql> CREATE PROCEDURE example(x INT) SELECT x + 1;
mysql> call example(1);
+---------+
| (x + 1) |
+---------+
| 2       |
+---------+

dolt_procedures table

mysql> select * from dolt_status;
+-----------------+--------+----------+
| table_name      | staged | status   |
+-----------------+--------+----------+
| dolt_procedures | 0      | modified |
+-----------------+--------+----------+
mysql> select * from dolt_procedures;
+---------+----------------------------------------------+----------------------------+----------------------------+
| name    | create_stmt                                  | created_at                 | modified_at                |
+---------+----------------------------------------------+----------------------------+----------------------------+
| example | CREATE PROCEDURE example(x INT) SELECT x + 1 | 2022-06-24 18:21:44.125045 | 2022-06-24 18:21:44.125045 |
+---------+----------------------------------------------+----------------------------+----------------------------+