You can do as yAnTar advised ALTER TABLE TABLE_NAME ADD Id INT AUTO_INCREMENT PRIMARY KEY OR You can add a constraint ALTER TABLE TABLE_NAME ADD CONSTRAINT constr_ID UNIQUE (user_id, game_id, date, time) But I think to not lose your existing data, you can add an indentity column and then make a composite key.
All keys are named, you should use something like this – ALTER TABLE tbl_quiz_attempt_master DROP INDEX index_name; To drop primary key use this one – ALTER TABLE tbl_quiz_attempt_master DROP INDEX `PRIMARY`; ALTER TABLE Syntax.
Specify a smaller length for your e-mail: $table->string(’email’, 250); Which is the default, actually: $table->string(’email’); And you should be good. For Laravel 5.4 you can find a solution in this Laravel 5.4: Specified key was too long error, Laravel News post: As outlined in the Migrations guide to fix this all you have to do … Read more
Yes, use INSERT … ON DUPLICATE KEY UPDATE id=id (it won’t trigger row update even though id is assigned to itself). If you don’t care about errors (conversion errors, foreign key errors) and autoincrement field exhaustion (it’s incremented even if the row is not inserted due to duplicate key), then use INSERT IGNORE like this: … Read more
KEY and INDEX are synonyms in MySQL. They mean the same thing. In databases you would use indexes to improve the speed of data retrieval. An index is typically created on columns used in JOIN, WHERE, and ORDER BY clauses. Imagine you have a table called users and you want to search for all the … Read more
Primary Key: There can only be one primary key constraint in a table In some DBMS it cannot be NULL – e.g. MySQL adds NOT NULL Primary Key is a unique key identifier of the record Unique Key: Can be more than one unique key in one table Unique key can have NULL values It … Read more
With Entity Framework 6.1, you can now do this: [Index(“IX_FirstAndSecond”, 1, IsUnique = true)] public int FirstColumn { get; set; } [Index(“IX_FirstAndSecond”, 2, IsUnique = true)] public int SecondColumn { get; set; } The second parameter in the attribute is where you can specify the order of the columns in the index. More information: MSDN