Check constraint in appian MYSQL database

Question

Hello, 
 
 I wonder if it is possible to apply check constraint in appian database? 
 
 Secondly, can it be possible to update the values in a table column based on the values in second column in the same table?

vimalkumars · Answer

xug0001 
 You will get this error, when the table already has some data and fails to qualify the check constraint requirements. Try to fix the data first and then create the check constraint. 
 
 I was able to re-produce the issue by following the scripts below 
 CREATE TABLE Persons (
 ID int NOT NULL,
 LastName varchar(255) NOT NULL,
 FirstName varchar(255),
 Age int,
 City varchar(255),
 PRIMARY Key (ID)
);

INSERT INTO `Persons` (`ID`, `LastName`, `FirstName`, `Age`, `City`) VALUES ('10', 'Test', 'Test', '17', 'Test');

ALTER TABLE Persons ADD CONSTRAINT CHK_PersonAge CHECK (Age>=18); 
-- This will throw the error message as you mentioned


-- Fix the data by using the blow query and create check constraint
UPDATE `Persons` SET `Age` = '18' WHERE `Persons`.`ID` = 10;
ALTER TABLE Persons ADD CONSTRAINT CHK_PersonAge CHECK (Age>=18);

Chris · Answer

CHECK constraint - if you have access to the database directly I don't see why you could not apply CHECK constraints where you would like, but note I am not a MySQL expert. 
 Additionally, you can certainly update values in a table column based on another. Utilize a!queryEntity() to retrieve data into your CDT, manipulate the CDT as needed, then Write to Datastore back to the DB. More details on your use case might be helpful here however.

Check constraint in appian MYSQL database

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