How to use DELIMITER in mariadb using the .NET MySql connector? - mysql

Question

I'm using MariaDB 10.2.12 and connecting using the .NET MySQL connector. The following trigger works fine in MySQL Workbench:
DELIMITER //
CREATE TRIGGER update_last_modified
BEFORE UPDATE ON users
FOR EACH ROW
BEGIN
DECLARE miscdataWithDate JSON;
IF JSON_CONTAINS_PATH(NEW.miscdata, 'all', '$.v1.lastModified2') THEN
SET NEW.miscdata = JSON_REPLACE(NEW.miscdata, '$.v1.lastModified2', UTC_TIMESTAMP());
ELSE
SET miscdataWithDate = JSON_SET('{"v1": {}}', '$.v1.lastModified2', UTC_TIMESTAMP());
SET NEW.miscdata = JSON_MERGE(NEW.miscdata, miscdataWithDate);
END IF;
END; //
DELIMITER ;
To run the command from C#/.NET, I used the following. I tried it with and without the final semicolon, in case the library is adding a semicolon:
using (var cmd = new MySqlCommand(#"CREATE TRIGGER update_last_modified
BEFORE INSERT ON users
FOR EACH ROW
BEGIN
DECLARE miscdataWithDate JSON;
IF JSON_CONTAINS_PATH(NEW.miscdata, 'all', '$.v1.lastModified') THEN
SET NEW.miscdata = JSON_REPLACE(NEW.miscdata, '$.v1.lastModified', UTC_TIMESTAMP());
ELSE
SET miscdataWithDate = JSON_SET('{""v1"": {}}', '$.v1.lastModified', UTC_TIMESTAMP());
SET NEW.miscdata = JSON_MERGE(NEW.miscdata, miscdataWithDate);
END IF;
END; //
DELIMITER ;", connection))
{
await cmd.ExecuteNonQueryAsync().ConfigureAwait(false);
}
When the trigger is defined (not called), the error is:
Unhandled Exception: System.AggregateException: One or more errors occurred. (You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '//
DELIMITER' at line 1) ---> MySql.Data.MySqlClient.MySqlException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '//
DELIMITER' at line 1
If I simplify the query so it doesn't need DELIMITER set, it works. But even a very simple trigger with a custom delimiter fails.

Answer 1

When searching for how other people have successfully used delimiters with MySQL/MariaDB from .NET, I found the following article: https://dev.mysql.com/doc/connector-net/en/connector-net-tutorials-mysqlscript-delimiter.html
The example given uses MySqlScript instead of MySqlCommand, and so I believe that MySqlCommand simply doesn't support delimiters. Here is the updated code, which works fine:
MySqlScript script = new MySqlScript(connection, #"CREATE TRIGGER update_last_modified
BEFORE INSERT ON users
FOR EACH ROW
BEGIN
DECLARE miscdataWithDate JSON;
IF JSON_CONTAINS_PATH(NEW.miscdata, 'all', '$.v1.lastModified') THEN
SET NEW.miscdata = JSON_REPLACE(NEW.miscdata, '$.v1.lastModified', UTC_TIMESTAMP());
ELSE
SET miscdataWithDate = JSON_SET('{""v1"": {}}', '$.v1.lastModified', UTC_TIMESTAMP());
SET NEW.miscdata = JSON_MERGE(NEW.miscdata, miscdataWithDate);
END IF;
END; //");
script.Delimiter = "//";
await script.ExecuteAsync().ConfigureAwait(false);