Table of Contents

Class DB2SqlExpressionConvertVisitor

Namespace
LinqToDB.Internal.DataProvider.DB2
Assembly
linq2db.dll
public class DB2SqlExpressionConvertVisitor : SqlExpressionConvertVisitor
Inheritance
object
DB2SqlExpressionConvertVisitor
Inherited Members
Extension Methods

Constructors

DB2SqlExpressionConvertVisitor(bool) 

public DB2SqlExpressionConvertVisitor(bool allowModify)

Parameters

allowModify bool

Properties

CanLowerIntervalDifference

Whether an elapsed date difference can be lowered to a value here.

public override bool CanLowerIntervalDifference { get; }

Property Value

bool

Remarks

Declared beside the lowering it describes, and read by the member translator through ITranslationContext.ProviderFlags. The translator has to ask before it builds anything, because a difference it does not build stays an ordinary .NET subtraction and is computed on materialisation - and by the time this visitor runs, the read expression is already bound to its columns, so there is no going back.

ConcatRequiresExplicitStringCast

When true (default), ConvertConcat(SqlConcatExpression) wraps every non-string operand in an explicit CAST(... AS VARCHAR(N)) before adding it to the concat chain. Required for providers whose concat operator is + (SQL Server pre-2025, SqlCe, Access) — SQL-standard data-type precedence would otherwise try to coerce string operands to the non-string side's type. Most providers whose final concat operator is || (PostgreSQL / Oracle / SQLite / SAP HANA / DuckDB / Firebird / DB2 / Informix / SQL Server 2025+) or CONCAT(...) function (MySQL / ClickHouse) auto-coerce non-string operands and override this to false for cleaner SQL. Sybase ASE is the exception: it emits || but keeps this true, since ASE requires an explicit convert() for non-character operands under both + and ||.

protected override bool ConcatRequiresExplicitStringCast { get; }

Property Value

bool

IntervalResolution

The tick count is built from MICROSECOND() scaled by ten, so it is a multiple of ten by construction and a component below the microsecond is identically zero rather than merely imprecise.

public override SqlIntervalUnit IntervalResolution { get; }

Property Value

SqlIntervalUnit

Remarks

Declared even though a column may be wider - timestamp(7) is what this fixture's model asks for - because what the measurement can distinguish is what the count is taken from, not what the column holds. The declined member falls back to .NET and answers from the two dates.

LikeCharactersToEscape

Characters with special meaning in LIKE predicate (defined by LikeCharactersToEscape) that should be escaped to be used as matched character. Default: ["%", "_", "?", "*", "#", "[", "]"].

public override string[] LikeCharactersToEscape { get; }

Property Value

string[]

SupportsNullIf 

protected override bool SupportsNullIf { get; }

Property Value

bool

SupportsNullInColumn 

protected override bool SupportsNullInColumn { get; }

Property Value

bool

Methods

ConvertConversion(SqlCastExpression)

Implements SqlCastExpression conversion.

protected override ISqlExpression ConvertConversion(SqlCastExpression cast)

Parameters

cast SqlCastExpression

Returns

ISqlExpression

ConvertSqlBinaryExpression(SqlBinaryExpression) 

public override IQueryElement ConvertSqlBinaryExpression(SqlBinaryExpression element)

Parameters

element SqlBinaryExpression

Returns

IQueryElement

ConvertSqlFunction(SqlFunction) 

public override ISqlExpression ConvertSqlFunction(SqlFunction func)

Parameters

func SqlFunction

Returns

ISqlExpression

ConvertSqlUnaryExpression(SqlUnaryExpression) 

public override ISqlExpression ConvertSqlUnaryExpression(SqlUnaryExpression element)

Parameters

element SqlUnaryExpression

Returns

ISqlExpression

ElapsedTicks(SqlIntervalDifferenceExpression)

Elapsed ticks summed from the three fields a DB2 timestamp decomposes into.

protected override ISqlExpression? ElapsedTicks(SqlIntervalDifferenceExpression element)

Parameters

element SqlIntervalDifferenceExpression

Returns

ISqlExpression

Remarks

TIMESTAMPDIFF is documented as an estimate - it assumes months of thirty days - so it cannot answer this. A timestamp is a whole number of days plus seconds since midnight plus microseconds, and each field's difference is exact, so their sum is the exact elapsed time. This is the same decomposition the provider's DateDiff lowering already uses.

IsWindowOrderByRequired(SqlExtendedFunction)

Every ranking function, NTILE, and LAG/LEAD - all of them SQL0104N ... Expected tokens may include: "ORDER BY" - plus any frame, which is SQL20117N A window specification for an OLAP function is not valid on its own. ROW_NUMBER and the *_VALUE pair are fine unordered, and so is an unframed aggregate.

protected override bool IsWindowOrderByRequired(SqlExtendedFunction func)

Parameters

func SqlExtendedFunction

Returns

bool

WrapColumnExpression(ISqlExpression) 

protected override ISqlExpression WrapColumnExpression(ISqlExpression expr)

Parameters

expr ISqlExpression

Returns

ISqlExpression