Check Constraint in MySQL Is Not Working

Mysql check Constraint does not work

Currently MySQL does not support check which means it parses your definition but ignores the check part.

The CHECK clause is parsed but ignored by all storage engines.

The docs

To achieve the same you can define a trigger and cancel the update/insert if necessary with a SIGNAL

SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Invalid P_Id';

But your actual problem here is that you don't define P_Id as auto-increment PRIMARY KEY. Then the DB does all for you.

Then you don't provide a P_Id at all. The DB numbers this column starting from 1.

_{And you actually should not use W3Schools. Their toturials are bad.}

SQL: Warning (Code 3819): Check constraint is violated makes no sense when using LOAD DATA LOCAL

You don't have the column names in the correct order in the LOAD DATA query.

LOAD DATA LOCAL INFILE "path_to_file_in_my_computer/Teams.csv"  
INTO TABLE test_schema.teams 
FIELDS TERMINATED BY ',' LINES TERMINATED BY '\r\n' 
IGNORE 1 LINES
(yearid, leagueid, teamid, @franchid, @divid, teamrank);

You can assign directly to the table column names, you don't need to use @yearID unless you have to do extra processing before storing in the table.

Unable to add check constraint to a column

Updated:

Just Create Table Without CHECK and Then After Alter it:

  create table jobs (
    JOB_ID varchar(10) not null,
    JOB_TITLE varchar(35) not null,
    MIN_SALARY decimal(6,0),
    MAX_SALARY decimal(6,0)
    );

---

ALTER TABLE jobs ADD CHECK (MAX_SALARY<=25000);

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OR

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In MySQL:

create table jobs (
    JOB_ID varchar(10) not null,
    JOB_TITLE varchar(35) not null,
    MIN_SALARY decimal(6,0),
    MAX_SALARY decimal(6,0), 
    CHECK(MAX_SALARY<=25000)    
    );

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SQL Server / Oracle

 create table jobs (
    JOB_ID varchar(10) not null,
    JOB_TITLE varchar(35) not null,
    MIN_SALARY decimal(6,0),
    MAX_SALARY decimal(6,0) CHECK(MAX_SALARY<=25000)

    );

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NOTE: CHECK constraints are not supported by MySQL But You Can Use it, as i declared , but its not give you an output !!

sql CHECK constraint not working properly

The CHECK constraint in MySQL is ignored as in Jakub Kania's answer

Example of working CHECK using SQL Server:

create table #schedule(order_date date,
dely_date date,
check(dely_date>order_date));

insert into #schedule values('2015-11-20','2014-12-25');
-- The INSERT statement conflicted with the CHECK constraint "CK_#schedule_A59B8DED". 
-- The conflict occurred in database "tempdb", table "dbo.#schedule___
-- __________________00000000C9D8". The statement has been terminated.

INSERT INTO #schedule values('2015-12-24','2015-12-25');

SELECT *
FROM #schedule;

LiveDemo

You can use trigger to do validation:

CREATE TABLE `schedule`(id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
                        order_date DATETIME,
                        dely_date DATETIME);              

CREATE TRIGGER `schedule_trg_ins` BEFORE INSERT ON `schedule`
FOR EACH ROW
BEGIN
    IF NOT(New.dely_date>New.order_date) THEN
    SIGNAL SQLSTATE '10000'
        SET MESSAGE_TEXT = 'check constraint on schedule failed during insert';
    END IF;
END;

CREATE TRIGGER `schedule_trg_upd` BEFORE UPDATE ON `schedule`
FOR EACH ROW
BEGIN
    IF NOT(New.dely_date>New.order_date) THEN
    SIGNAL SQLSTATE '10000'
        SET MESSAGE_TEXT = 'check constraint on schedule failed during update';
    END IF;
END;

INSERT INTO `schedule`(order_date, dely_date)
VALUES ('2015-12-24','2015-12-25');

INSERT INTO `schedule`(order_date, dely_date)
VALUES ('2015-12-26','2015-12-25');
-- check constraint on schedule failed during insert

UPDATE `schedule`
SET order_date = '2015-12-26'
WHERE id = 1;
-- check constraint on schedule failed during update

SqlFiddleDemo

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