AbsDB SQL Logical operators

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AbsDB SQL Logical operators

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Logical Operators

Absolute Database supports usual logical operators:

Operator

Description

Example

AND

Both conditions must apply

(ID > 1) AND (ID < 100)

OR

Either condition can apply

(Color = 'Blue') OR (Color = 'Red')

NOT

Logical opposite of condition

NOT (State = 'CA')

SQL uses a three-valued Boolean logic where the null value represents "unknown".

 

Observe the following truth tables:

a

b

a AND b

a OR b

TRUE

TRUE

TRUE

TRUE

TRUE

FALSE

FALSE

TRUE

TRUE

NULL

NULL

TRUE

FALSE

FALSE

FALSE

FALSE

FALSE

NULL

FALSE

NULL

NULL

NULL

NULL

NULL

 

 

 

 

a

NOT a

 

 

TRUE

FALSE

 

 

FALSE

TRUE

 

 

NULL

NULL

 

 

 

The operators AND and OR are commutative, that is, you can switch the left and right operand without affecting the result.

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27-10-2017 - Niels Knabe