---
title: "Logical Expressions (XQuery) | Microsoft Docs"
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ms.date: "03/14/2017"
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  - "logical operators [SQL Server], XQuery"
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---
# Logical Expressions (XQuery)
[!INCLUDE[tsql-appliesto-ss2012-xxxx-xxxx-xxx-md](../includes/tsql-appliesto-ss2012-xxxx-xxxx-xxx-md.md)]

  XQuery supports the logical **and** and **or** operators.  
  
```  
expression1 and expression2  
expression1 or expression2  
```  
  
 The test expressions, `expression1,``expression2`, in [!INCLUDE[ssNoVersion](../includes/ssnoversion-md.md)] can result in an empty sequence, a sequence of one or more nodes, or a single Boolean value. Based on the result, their effective Boolean value is determined in the following manner:  
  
-   If the test expression results in an empty sequence, the result of the expression is False.  
  
-   If the test expression results in a single Boolean value, this value is the result of the expression.  
  
-   If the test expression results in a sequence of one or more nodes, the result of the expression is True.  
  
-   Otherwise, a static error is raised.  
  
 The logical **and** and **or** operator is then applied to the resulting Boolean values of the expressions with the standard logical semantics.  
  
 The following query retrieves from the product catalog the front-angle small pictures, the <`Picture`> element, for a specific product model. Note that for each product description document, the catalog can store one or more product pictures with different attributes, such as size and angle.  
  
```  
SELECT CatalogDescription.query('  
     declare namespace PD="https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription";  
     for $F in /PD:ProductDescription/PD:Picture[PD:Size="small"   
                                                 and PD:Angle="front"]  
     return   
         $F   
    ') as Result  
FROM  Production.ProductModel  
where ProductModelID=19  
```  
  
 This is the result:  
  
```  
<PD:Picture   
  xmlns:PD="https://schemas.microsoft.com/sqlserver/2004/07/adventure-works/ProductModelDescription">  
  <PD:Angle>front</PD:Angle>  
  <PD:Size>small</PD:Size>  
  <PD:ProductPhotoID>31</PD:ProductPhotoID>  
</PD:Picture>  
  
```  
  
## See Also  
 [XQuery Expressions](../xquery/xquery-expressions.md)