Class MySqlSqlExpressionConvertVisitor
- Namespace
- LinqToDB.Internal.DataProvider.MySql
- Assembly
- linq2db.dll
public class MySqlSqlExpressionConvertVisitor : SqlExpressionConvertVisitor- Inheritance
-
objectMySqlSqlExpressionConvertVisitor
- Derived
- Inherited Members
- Extension Methods
Constructors
MySqlSqlExpressionConvertVisitor(bool)
public MySqlSqlExpressionConvertVisitor(bool allowModify)Parameters
allowModifybool
Properties
CanLowerIntervalDifference
Whether an elapsed date difference can be lowered to a value here.
public override bool CanLowerIntervalDifference { get; }Property Value
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.
CanLowerIntervalShift
Whether LowerTemporalArithmetic(SqlTemporalArithmeticExpression) can express a date shifted by an interval at all.
public override bool CanLowerIntervalShift { get; }Property Value
Remarks
Read by the member translator so a declared duration added to a date is declined while the expression is still being built, rather than reaching the builder as a node nothing can render - a refusal there has no client-side fallback left. The default follows what the base implementation needs: it spends the amount through ShiftDate(SqlIntervalUnit, ISqlExpression, ISqlExpression) at FinestDateUnit, so a provider that names no finest unit cannot lower one.
Only the declared half is declined early. A shift by a computed difference is left to be built,
because start + (end - start) cancels against the difference it came from and asks the provider
for nothing - refusing it here would sink a query that works everywhere.
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
Methods
ConvertConversion(SqlCastExpression)
Implements SqlCastExpression conversion.
protected override ISqlExpression ConvertConversion(SqlCastExpression cast)Parameters
castSqlCastExpression
Returns
ConvertSearchStringPredicate(SearchString)
public override ISqlPredicate ConvertSearchStringPredicate(SqlPredicate.SearchString predicate)Parameters
predicateSqlPredicate.SearchString
Returns
ConvertSqlBinaryExpression(SqlBinaryExpression)
public override IQueryElement ConvertSqlBinaryExpression(SqlBinaryExpression element)Parameters
elementSqlBinaryExpression
Returns
ConvertSqlFunction(SqlFunction)
public override ISqlExpression ConvertSqlFunction(SqlFunction func)Parameters
funcSqlFunction
Returns
ElapsedTicks(SqlIntervalDifferenceExpression)
Elapsed ticks from TIMESTAMPDIFF at microsecond resolution.
protected override ISqlExpression? ElapsedTicks(SqlIntervalDifferenceExpression element)Parameters
elementSqlIntervalDifferenceExpression
Returns
Remarks
A microsecond is the finest unit MySQL stores, so the count is exact and scaling it to ticks - ten of
them to the microsecond - loses nothing. The result is a BIGINT of microseconds, which runs out
far beyond any range TimeSpan can hold.
LowerTemporalArithmetic(SqlTemporalArithmeticExpression)
Shifts through DATE_ADD at microsecond resolution - the interval's own unit here.
protected override ISqlExpression? LowerTemporalArithmetic(SqlTemporalArithmeticExpression element)Parameters
elementSqlTemporalArithmeticExpression
Returns
Remarks
The amount is an expression rather than a literal, and MySQL takes it as written, so the whole tick count converts in one step with no decomposition into coarser units.
TruncateDivide(ISqlExpression, long)
DIV, because MySQL's / is a decimal division even between two integers.
protected override ISqlExpression TruncateDivide(ISqlExpression value, long divisor)Parameters
valueISqlExpressiondivisorlong
Returns
WrapColumnExpression(ISqlExpression)
protected override ISqlExpression WrapColumnExpression(ISqlExpression expr)Parameters
exprISqlExpression