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Structure

SQLConflictResolutionStrategy

Specifies a conflict resolution strategy and associated conditions for an INSERT query. An INSERT with a conflict strategy is often refered to as an UPSERT (“insert or update”). Databases are not required to support any given subset of upsert functionality, or any at all.
struct SQLConflictResolutionStrategy

Overview

Unfortunately, in MySQL the “no action” strategy must use INSERT IGNORE, which appears in a completely different place in the query than the update strategy. For now, this is implemented by providing an additional expression that SQLInsert has to embed at the appropriate point if provided, which is gated on both the dialect’s syntax and the conflict action. There hasn’t been a need to deal with this particular kind of syntax issue before, so this method of handling it is something of an experiment.

Topics

Initializers

Instance Properties

  • action
    An action to take to resolve a conflict in the unique index.
  • targetColumns
    The column or columns which comprise the uniquness constraint to which the strategy should apply. The exact rules for how a matching constraint is found when an exact match is not found vary between databases. Not all database implement conflict targets.

Instance Methods

  • queryModifier(for:)
    An expression to be embedded into the same INSERT query as the strategy expression to work around MySQL’s desire to make life difficult.
  • serialize(to:)
    Invoked when a request is made to serialize the expression to raw SQL.

Relationships

Conforms To

See Also

Clause Expressions

  • SQLAlterColumnDefinitionType
    A clause specifying a new data type to be applied to an existing column.
  • SQLColumnAssignment
    Encapsulates a column_name=value expression in the context of an UPDATE query’s value assignment list. This is distinct from an SQLBinaryExpression using the .equal operator in that the left side must be an unqualified column name, the operator must be =, and the right side may use SQLExcludedColumn when the assignment appears in the assignments list of a SQLConflictAction.update(assignments:predicate:) specification.
  • SQLColumnConstraintAlgorithm
    Column-level data constraints.
  • SQLColumnDefinition
    A clause expressing a column definition, for use when creating and altering tables.
  • SQLConflictAction
    An action to take when an INSERT query encounters a unique constraint violation.
  • SQLDropBehavior
    Specifies a behavior when performing a DROP operation on a database object which is referenced by other objects.
  • SQLEnumDataType
    Represents a data type which specifies an enumeration in the database.
  • SQLExcludedColumn
    An expression appearing on the right side of a column assignment which, when the assignment list is part of an upsert’s update acion, refers to the value which was originally to be inserted for the given column.
  • SQLForeignKey
    A complete FOREIGN KEY constraint specification.
  • SQLInsertModifier
    Simple helper for working around MySQL’s refusal to implement standard SQL. Only emits SQL when needed.
  • SQLJoin
    Encapsulates a single SQL JOIN, specifying the join type, the right-side table, and condition.
  • SQLJoinMethod
    The method used by a table join clause.
  • SQLLockingClause
    An SQL locking clause.
  • SQLOrderBy
    A pair of expressions, one describing a query sort key and the other a directionality for that key.
  • SQLReturning
    A clause describing a list of values to be returned from a data-modifying query.