What do the curly braces mean in a MySQL statement?-CodePudding

I have query from Business Object report that run in MySQL database

CREATE TABLE `mytable` (`date_type_column` date DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `mytable`(`date_type_column`) VALUES ('2019-01-02');
INSERT INTO `mytable`(`date_type_column`) VALUES ('2020-01-02');
INSERT INTO `mytable`(`date_type_column`) VALUES ('2021-01-02');
INSERT INTO `mytable`(`date_type_column`) VALUES ('2022-01-02');


SELECT
*
FROM
`mytable`
WHERE
date_type_column >= {d '2021-01-01 00:00:00'};

the question is what does {d '2022-02-01 00:00:00'} syntax actually mean in this statemen ? It may be not correct SQL syntax but the query works "as is" in MySQL workbench 8.0. MySQL 5.7.39.

CodePudding user response：

This is ODBC escape syntax. It's described in the Expressions documentation:

{identifier expr} is ODBC escape syntax and is accepted for ODBC compatibility. The value is expr. The { and } curly braces in the syntax should be written literally; they are not metasyntax as used elsewhere in syntax descriptions.

SQL-Server uses the identifier to determine how to parse expr. d is used to create DATE literals. See the SQL-Server documentation Date, Time, and Timestamp Literals. But MySQL ignores the identifier.

I can't explain why the query doesn't work for 2022 dates, it should be no different from writing

WHERE
mytable.mydate_Type_column >= '2022-02-01 00:00:00'

without the curly braces.