Cannot Alter Table Constraint on Mysql <p>anyone knows, i tried so many times to use alter table constraint in my mysql sql.</p> <p>So i want to alter table constraint to add validation in gender column :</p> <pre><code>alter table jewerly add constraint checkGender CHECK(Gender='Male' OR Gender='female'); </code></pre> <p>is that right ? i dont know what is the problem but it always return empty result on my mysql. why ?</p> <p>i read from another thread, it said that is normal if return empty result.</p> <p>but i try to export my sql and i see no contraint query added on my sql.</p> <p>anyone knows the problem ?</p> <p>======</p> <p>Note : it marked as duplicate question, but the last thread only has sollution for checking gender constraint, how about if i want to add another constraint ? the constraint always missing after we add it.</p>