Tag: databases

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UPDATE the records in the table

MODIFY the data type of the column

DROP the table column

DEFINE a default value for the column

DELETE the records in the table

ADD a new column to the table

TRUNCATE is DDL and DELETE is DML

TRUNCATE is DML and DELETE is DDL

TRUNCATE is DCL and DELETE is DML

TRUNCATE is DML and DELETE is DCL

Can be defined on a single column or multiple columns in the table.

Can be defined only on a single column in the table.

A UNIQUE index is automatically created once PRIMARY KEY is defined on the table.

A NON-UNIQUE index is automatically created once PRIMARY KEY is defined on the table.

NOT NULL constraint is implicitly enforced on the columns which are part of the PRIMARY KEY

NULL constraint is implicitly enforced on the columns which are part of the PRIMARY KEY

Can be defined only on a single column in the table.

Can be defined on a single column or multiple columns in the table.

A UNIQUE index is automatically created once UNIQUE KEY is defined on the table.

A NON-UNIQUE index is automatically created once UNIQUE KEY is defined on the table.

NULL values are NOT acceptable on the columns, which are part of UNIQUE KEY

NULL values are acceptable, which are part of UNIQUE KEY

Must be defined as a part of column definition

It's NOT necessary to define it as a part of column definition

Can be applied to the column which may hold UNKNOWN data

Can NOT be applied to the column which may hold UNKNOWN data

Must evaluate to BOOLEAN expression

Not necessarily evaluates to BOOLEAN expression

Requires that a column (or combination of columns) satisfy a condition for every row in the table excluding nulls.

Columns which, are part of CHECK constraint, may accept NULL values

Columns which, are part of CHECK constraint, can NOT accept NULL values

Defines relations between the tables

The table that includes the foreign key is called the dependent or child table

The table that includes the foreign key is called the parent table

The table that is referenced by the foreign key is called the parent table

The table that is referenced by the foreign key is called the dependent or child table

True

False

True

False