Expressions

Table of Contents



Expressions can be used in the field list of a Select, in Insert values, in Update assignments and in Where clauses.

  • Numbers: 10, -6, 3.14159
  • Strings: 'single quoted' or "double quoted". A doubled quote ('It''s') is not supported. A quote that follows a backslash does not end the string, but the backslash is kept: 'It's' returns It's.
  • Null: null


Operator Meaning
+ Adds numbers. When either side is a string, the values are concatenated: 'Id: ' + 5 returns 'Id: 5'.
- * / Subtraction, multiplication and division.
% Remainder (modulo).
Bitwise exclusive-or. Use Pow for exponentiation.
( ) Grouping, with standard order of operations.

A null on either side of + makes the result null (null propagation). Concat skips nulls instead.

These are used in Where clauses and join ON conditions:
Operator Meaning
= Equal (strings are compared without regard to case).
!= Not equal. The <> form is not supported.
> >= < <= Numeric comparisons.
LIKE, NOT LIKE Pattern matching, see Like.
BETWEEN, NOT BETWEEN Range matching, see Between.

Comparison operators can only be used in WHERE and ON clauses. Elsewhere, use the boolean functions such as IsEqual, IsGreater and IsLike, which return 1 or 0.

-- A line comment.
SELECT Id, Name FROM WordList:Language -- A trailing comment.
/* A block
   comment. */


Use Declare to define a variable for the rest of the script. Variables are referenced with an @ prefix. Applications using the client API pass parameters the same way, see Client.
DECLARE @Language = 2
SELECT Text FROM WordList:Word WHERE LanguageId = @Language


Every SELECT needs a FROM clause. To evaluate expressions that don't read any documents, select from the built-in Single schema, which contains exactly one document.
SELECT 10 + 10 as Twenty, 'Hello' + ' ' + 'World' as Greeting, Guid() as Id FROM Single




SQL :: ToProper
Returns the value with the first letter of each word capitalized (title case).
SQL :: ToString
Returns the number as a string, so that + concatenates it instead of adding it.
SQL :: ToUpper
Returns the value converted to upper case.
SQL :: Transaction
Transactions make a group of statements all-or-nothing.
SQL :: Trim
Removes white space from the start and end of the value. When characters is given, each of those characters is removed from the start and end instead.
SQL :: Update
Update changes fields of existing documents.
SQL :: Variance
Returns the population variance of the values in each group: how far the values are spread from their mean.
SQL :: Where
The where clause filters the documents read, updated or deleted by a statement.