NOT NULL
- Indicated that column cannot contain any NULL value
'COLUMN1' 'DATA_TYPE(SIZE)' NOT NULL
UNIQUE
- Does not allow to insert a duplicate value in a column
- More than one UNIQUE column can be used in a table
PRIMARY KEY
- Enforced the table to accept unique data for a specific column
- for accessing the table faster
CHECK
- Determined whether the value is valid or not from a logical expression
DEFAULT
- While inserting data into a table, if no value is supplied to a column, then the column gets the value set as DEFAULT
AUTO INCREMENT
- allow a unique number to be generated when a new record is inserted into a table
- By default, the starting value for AUTO_INCREMENT is 1, and it will increment by 1 for each new record
'COLUMN1' 'DATATYPE' NOT NULL AUTO_INCREMENT;