SQLExpression

public protocol SQLExpression : SQLSpecificExpressible, SQLSelectable, SQLOrderingTerm

Experimental

SQLExpression is the protocol for types that represent an SQL expression, as described at https://www.sqlite.org/lang_expr.html

GRDB ships with a variety of types that already adopt this protocol, and allow to represent many SQLite expressions:

  • Column
  • DatabaseValue
  • SQLExpressionLiteral
  • SQLExpressionUnary
  • SQLExpressionBinary
  • SQLExpressionExists
  • SQLExpressionFunction
  • SQLExpressionCollate

  • Experimental

    Returns an SQL string that represents the expression.

    When the arguments parameter is nil, any value must be written down as a literal in the returned SQL:

    var arguments: StatementArguments? = nil
let expression = "foo'bar".databaseValue
expression.expressionSQL(&arguments)  // "'foo''bar'"

    When the arguments parameter is not nil, then values may be replaced by ? or colon-prefixed tokens, and fed into arguments.

    var arguments = StatementArguments()
let expression = "foo'bar".databaseValue
expression.expressionSQL(&arguments)  // "?"
arguments                             // ["foo'bar"]

    Declaration

    Swift

    func expressionSQL(_ arguments: inout StatementArguments?) -> String
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  • negated Default implementation

    Experimental

    Returns the expression, negated. This property fuels the ! operator.

    The default implementation returns the expression prefixed by NOT.

    let column = Column("favorite")
column.negated  // NOT favorite

    Some expressions may provide a custom implementation that returns a more natural SQL expression.

    let expression = [1,2,3].contains(Column("id")) // id IN (1,2,3)
expression.negated // id NOT IN (1,2,3)

    Default Implementation

    Experimental

    The default implementation returns the expression prefixed by NOT.

    let column = Column("favorite")
column.negated  // NOT favorite

    Declaration

    Swift

    var negated: SQLExpression
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  • matchedRowIds(rowIdName:) Default implementation

    Experimental

    Returns the rowIds matched by the expression.

    Default Implementation

    Experimental

    The default implementation returns nil

    Declaration

    Swift

    func matchedRowIds(rowIdName: String?) -> Set<Int64>?
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