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6. Querying > Combining expressions

Combining expressions

Multiple select expressions can be combined using: INTERSECTION, OR, AND, NOT, and parentheses ( ).

<select expression> intersection <select expression>
NOT <select expression>
(<select expression>)
<select expression> or <select expression>
<select expression> and <select expression>

SimpleDB supports both the set operators—INTERSECTION and UNION. The INTERSECTION operator can be used to retrieve items matching the specified predicates on both sides of the operator. The UNION operator is used for retrieving items that match either of the specified predicates. The UNION operator works only with the old query syntax and will not work with the new Select syntax. You should use the OR operator instead of UNION.


  

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