ISqlDialect

BatchSeparator

public string BatchSeparator { get; }

value = iSqlDialect.BatchSeparator

Batch separator (e.g. GO for SQL Server). Empty when no separation is needed.

BooleanCastSqlType

public string BooleanCastSqlType { get; }

value = iSqlDialect.BooleanCastSqlType

SQL type name to cast a boolean expression to when materialising EXISTS(...) projections (e.g. bit on SQL Server). Return if the dialect represents booleans natively and no cast is needed (e.g. PostgreSQL).

CanAlterColumn

public bool CanAlterColumn { get; }

value = iSqlDialect.CanAlterColumn

Whether an existing column's type or nullability can be changed in place. SQLite cannot: such a change means rebuilding the table.

CanAlterColumnWithDependents

public bool CanAlterColumnWithDependents { get; }

value = iSqlDialect.CanAlterColumnWithDependents

Whether ALTER COLUMN can change a column that an index, a primary key or a foreign key depends on. SQL Server cannot: those have to be dropped before and recreated after.

ConcatOperator

public string ConcatOperator { get; }

value = iSqlDialect.ConcatOperator

SQL string concatenation operator.

DecimalComparisonCastSqlType

public string DecimalComparisonCastSqlType { get; }

value = iSqlDialect.DecimalComparisonCastSqlType

SQL type name used to cast decimal operands before comparisons when the dialect stores decimals in a non-numeric affinity. Return when no comparison cast is required.

EmptyBinaryLiteral

public string EmptyBinaryLiteral { get; }

value = iSqlDialect.EmptyBinaryLiteral

SQL literal for an empty binary value (e.g. 0x for SQL Server, X'' for the SQL standard, an empty bytea for PostgreSQL).

FalseLiteral

public string FalseLiteral { get; }

value = iSqlDialect.FalseLiteral

SQL literal for boolean false.

IsNullFunction

public string IsNullFunction { get; }

value = iSqlDialect.IsNullFunction

Function name for null-coalescing.

KeepsDecimalDigits

public bool KeepsDecimalDigits { get; }

value = iSqlDialect.KeepsDecimalDigits

Whether a decimal column keeps a declared precision and scale. A dialect that stores decimals as text keeps neither, so there is nothing to compare a declaration against.

LenFunction

public string LenFunction { get; }

value = iSqlDialect.LenFunction

Function name for string length.

MaxParameters

public int MaxParameters { get; }

value = iSqlDialect.MaxParameters

Maximum number of parameters allowed in a single statement. SQL Server: 2100, SQLite: 999, PostgreSQL: 65535, MySQL: 65535.

ParameterPrefix

public string ParameterPrefix { get; }

value = iSqlDialect.ParameterPrefix

Parameter prefix (e.g. @ for SQL Server, $ for PostgreSQL).

SupportsAddForeignKeyViaAlter

public bool SupportsAddForeignKeyViaAlter { get; }

value = iSqlDialect.SupportsAddForeignKeyViaAlter

True when this dialect can add a foreign key to an existing table via String). When false (SQLite), a foreign key can only be declared inline inside CREATE TABLE, so the migrator keeps new-table FKs inline and creates the referenced tables first.

SupportsInsertReturning

public bool SupportsInsertReturning { get; }

value = iSqlDialect.SupportsInsertReturning

True when this dialect can return a server-generated identity in the same statement via String); callers use it to choose between a single-statement INSERT…RETURNING and a two-statement INSERT + SELECT identity batch.

TrueLiteral

public string TrueLiteral { get; }

value = iSqlDialect.TrueLiteral

SQL literal for boolean true.

UnicodePrefix

public string UnicodePrefix { get; }

value = iSqlDialect.UnicodePrefix

Unicode string-literal prefix (e.g. N for SQL Server).

AppendAddColumn

public void AppendAddColumn(StringBuilder sb, string tableName, string columnName, string columnDef)

iSqlDialect.AppendAddColumn(sb, tableName, columnName, columnDef)

Appends ALTER TABLE ADD COLUMN.

AppendAddForeignKey

public void AppendAddForeignKey(StringBuilder sb, string tableName, string columnName, string refTableName, string refColumnName)

iSqlDialect.AppendAddForeignKey(sb, tableName, columnName, refTableName, refColumnName)

Appends an ALTER TABLE ADD CONSTRAINT for a new foreign key.

AppendAlterColumn

public void AppendAlterColumn(StringBuilder sb, string tableName, string columnName, Type clrType, bool isNullable, int maxLength, int precision, int scale, DbColumnInfo live)

iSqlDialect.AppendAlterColumn(sb, tableName, columnName, clrType, isNullable, maxLength, precision, scale, live)

Appends ALTER TABLE ALTER COLUMN that gives a column the declared type and nullability.

sb

Where the statement goes.

tableName

The table.

columnName

The column.

clrType

The property type the column holds.

isNullable

Whether the column should allow NULLs.

maxLength

The declared length, 0 for the default.

precision

The declared precision, 0 for the default.

scale

The declared scale.

live

The column as the database holds it, or null for a column this script has just added; a dialect uses it to keep what the declaration does not decide, and to convert the stored values.

AppendAlterNullability

public void AppendAlterNullability(StringBuilder sb, string tableName, string columnName, bool isNullable, DbColumnInfo live)

iSqlDialect.AppendAlterNullability(sb, tableName, columnName, isNullable, live)

Makes a column nullable or not, leaving its type as the database holds it.

sb

Where the statement goes.

tableName

The table.

columnName

The column.

isNullable

Whether the column should allow NULLs.

live

The column as the database holds it.

AppendCreateIndex

public void AppendCreateIndex(StringBuilder sb, string indexName, string tableName, string columnName, bool unique)

iSqlDialect.AppendCreateIndex(sb, indexName, tableName, columnName, unique)

Appends a CREATE INDEX (or CREATE UNIQUE INDEX) on a single column.

AppendCreateTable

public void AppendCreateTable(StringBuilder sb, string tableName, string columnDefs)

iSqlDialect.AppendCreateTable(sb, tableName, columnDefs)

Appends CREATE TABLE [IF NOT EXISTS] statement.

AppendDateAdd

public void AppendDateAdd(StringBuilder sb, string part, string amountSql, string sourceSql)

iSqlDialect.AppendDateAdd(sb, part, amountSql, sourceSql)

Appends a DATEADD-style expression.

AppendDateDiff

public void AppendDateDiff(StringBuilder sb, string part, string startSql, string endSql)

iSqlDialect.AppendDateDiff(sb, part, startSql, endSql)

Appends a DATEDIFF-style expression computing minus , expressed in units.

sb

Target builder.

part

Unit of the result: year, month, week, day, hour, minute, second or millisecond.

startSql

SQL of the start date.

endSql

SQL of the end date.

AppendDatePartClose

public void AppendDatePartClose(StringBuilder sb)

iSqlDialect.AppendDatePartClose(sb)

Closes a date-part extraction expression opened by String).

AppendDatePartOpen

public void AppendDatePartOpen(StringBuilder sb, string part)

iSqlDialect.AppendDatePartOpen(sb, part)

Opens a date-part extraction expression (closed by StringBuilder)).

AppendDecimalModulo

public void AppendDecimalModulo(StringBuilder sb, string dividendSql, string divisorSql)

iSqlDialect.AppendDecimalModulo(sb, dividendSql, divisorSql)

Appends the remainder of dividing one decimal value by another, fraction included and with the sign of the dividend, as the C# % operator gives it.

sb

Target builder.

dividendSql

SQL of the dividend.

divisorSql

SQL of the divisor.

AppendDeleteBy

public void AppendDeleteBy(StringBuilder sb, string tableName, string[] whereColumns)

iSqlDialect.AppendDeleteBy(sb, tableName, whereColumns)

Appends a DELETE … WHERE statement.

AppendDropColumn

public void AppendDropColumn(StringBuilder sb, string tableName, string columnName)

iSqlDialect.AppendDropColumn(sb, tableName, columnName)

Appends ALTER TABLE DROP COLUMN.

AppendDropForeignKey

public void AppendDropForeignKey(StringBuilder sb, string tableName, string constraintName)

iSqlDialect.AppendDropForeignKey(sb, tableName, constraintName)

Appends an ALTER TABLE DROP CONSTRAINT for an existing foreign key.

AppendDropIndex

public void AppendDropIndex(StringBuilder sb, string tableName, string indexName)

iSqlDialect.AppendDropIndex(sb, tableName, indexName)

Appends DROP INDEX.

AppendDropTable

public void AppendDropTable(StringBuilder sb, string tableName)

iSqlDialect.AppendDropTable(sb, tableName)

Appends DROP TABLE [IF EXISTS] statement.

AppendFallbackOrderBy

public void AppendFallbackOrderBy(StringBuilder sb)

iSqlDialect.AppendFallbackOrderBy(sb)

Appends a fallback ORDER BY clause when there is neither explicit ordering nor an identity column. SQL Server requires ORDER BY for OFFSET/FETCH; other dialects may emit a deterministic shim or nothing at all.

AppendGreatest

public void AppendGreatest(StringBuilder sb, string leftSql, string rightSql)

iSqlDialect.AppendGreatest(sb, leftSql, rightSql)

Appends the larger of two values, the way Decimal) picks it: a scalar function of two arguments, not the MAX aggregate.

sb

Target builder.

leftSql

SQL of the first value.

rightSql

SQL of the second value.

AppendInsertReturningClause

public void AppendInsertReturningClause(StringBuilder sb, string idColumn)

iSqlDialect.AppendInsertReturningClause(sb, idColumn)

Appends a dialect-specific RETURNING clause to an INSERT, scoped to the given identity column. PostgreSQL emits RETURNING "Id"; SQL Server and SQLite have other identity-read mechanisms and emit nothing here.

AppendLeast

public void AppendLeast(StringBuilder sb, string leftSql, string rightSql)

iSqlDialect.AppendLeast(sb, leftSql, rightSql)

Appends the smaller of two values, the way Decimal) picks it: a scalar function of two arguments, not the MIN aggregate.

sb

Target builder.

leftSql

SQL of the first value.

rightSql

SQL of the second value.

AppendPagination

public void AppendPagination(StringBuilder sb, long? skip, long? take, bool hasOrderBy)

iSqlDialect.AppendPagination(sb, skip, take, hasOrderBy)

Appends literal pagination (LIMIT/OFFSET or OFFSET/FETCH) with values.

AppendPaginationParams

public void AppendPaginationParams(StringBuilder sb, string skipParamExpr, string takeParamExpr)

iSqlDialect.AppendPaginationParams(sb, skipParamExpr, takeParamExpr)

Appends parameterised pagination with already-prefixed parameter expressions (e.g. @skip, @take).

AppendRound

public void AppendRound(StringBuilder sb, string valueSql, string digitsSql, MidpointRounding mode)

iSqlDialect.AppendRound(sb, valueSql, digitsSql, mode)

Appends an expression that rounds a value the way MidpointRounding) does with the given mode.

sb

Target builder.

valueSql

SQL of the value.

digitsSql

SQL of the number of fractional digits to keep, or to round to a whole number.

mode

How the value is rounded; ToZero truncates.

AppendSetCompression

public void AppendSetCompression(StringBuilder builder, string tableName, DataCompressions compression)

iSqlDialect.AppendSetCompression(builder, tableName, compression)

Writes the statement that repacks a table.

builder

Where the statement is written.

tableName

Table to repack.

compression

The packing to apply.

AppendTrimClose

public void AppendTrimClose(StringBuilder sb)

iSqlDialect.AppendTrimClose(sb)

Closes a TRIM expression opened by StringBuilder).

AppendTrimOpen

public void AppendTrimOpen(StringBuilder sb)

iSqlDialect.AppendTrimOpen(sb)

Opens a TRIM expression (closed by StringBuilder)).

AppendUpdateBy

public void AppendUpdateBy(StringBuilder sb, string tableName, string[] setColumns, string[] whereColumns)

iSqlDialect.AppendUpdateBy(sb, tableName, setColumns, whereColumns)

Appends an UPDATE … SET … WHERE statement.

AppendUpdateWhereNull

public void AppendUpdateWhereNull(StringBuilder sb, string tableName, string columnName, string defaultLiteral)

iSqlDialect.AppendUpdateWhereNull(sb, tableName, columnName, defaultLiteral)

Appends UPDATE … SET column = literal WHERE column IS NULL — used during migrations to fill default values before altering nullability.

AppendUpsert

public void AppendUpsert(StringBuilder sb, string tableName, string[] allColumns, string[] keyColumns)

iSqlDialect.AppendUpsert(sb, tableName, allColumns, keyColumns)

Appends a UPSERT statement (MERGE on SQL Server, INSERT … ON CONFLICT on PostgreSQL/SQLite).

ConvertFromDbValue

public object ConvertFromDbValue(object value, Type targetType)

result = iSqlDialect.ConvertFromDbValue(value, targetType)

Converts a database value to the requested CLR target type.

ConvertToDbValue

public object ConvertToDbValue(object value, Type clrType)

result = iSqlDialect.ConvertToDbValue(value, clrType)

Converts a CLR value to the form a database driver expects.

FormatSkip

public string FormatSkip(string skip)

result = iSqlDialect.FormatSkip(skip)

Renders a SKIP/OFFSET clause from a parameter expression.

FormatTake

public string FormatTake(string take)

result = iSqlDialect.FormatTake(take)

Renders a TAKE/FETCH clause from a parameter expression.

GetColumnDefinition

public string GetColumnDefinition(Type clrType, bool isNullable, int maxLength, int precision, int scale)

result = iSqlDialect.GetColumnDefinition(clrType, isNullable, maxLength, precision, scale)

Full column definition: SQL type + NULL/NOT NULL.

GetColumnTypeName

public string GetColumnTypeName(Type clrType, int maxLength, int precision, int scale)

result = iSqlDialect.GetColumnTypeName(clrType, maxLength, precision, scale)

The SQL type a column is created with: the type name together with its length, precision or scale. A decimal that declares only a scale gets DefaultDecimalPrecision; one that declares a precision keeps its scale as declared, zero included.

GetDefaultLiteral

public string GetDefaultLiteral(Type clrType)

result = iSqlDialect.GetDefaultLiteral(clrType)

Returns a SQL literal representing the default value for the given CLR type. Used during migrations to backfill NOT NULL columns.

GetForeignKeyConstraint

public string GetForeignKeyConstraint(string tableName, string columnName, string refTableName, string refColumnName)

result = iSqlDialect.GetForeignKeyConstraint(tableName, columnName, refTableName, refColumnName)

Inline FOREIGN KEY constraint clause for use inside CREATE TABLE.

GetIdentityColumnSuffix

public string GetIdentityColumnSuffix(string pkConstraintName)

result = iSqlDialect.GetIdentityColumnSuffix(pkConstraintName)

Same as GetIdentityColumnSuffix, but names the PRIMARY KEY constraint. Without a name the database invents one — PK__Table__hash on SQL Server, table_pkey on PostgreSQL — which no naming convention can match.

pkConstraintName

Constraint name, normally from String).

戻り値: The column-definition suffix carrying the named constraint.

GetIdentityColumnSuffix

public string GetIdentityColumnSuffix()

result = iSqlDialect.GetIdentityColumnSuffix()

Suffix for an identity (auto-increment primary key) column definition.

GetIdentitySelect

public string GetIdentitySelect(string idCol)

result = iSqlDialect.GetIdentitySelect(idCol)

SQL expression that returns the identity value of the last insert.

GetIntegerToDecimalCastSqlType

public string GetIntegerToDecimalCastSqlType(int precision)

result = iSqlDialect.GetIntegerToDecimalCastSqlType(precision)

SQL type a whole number is cast to when a query converts it to Decimal.

precision

Number of digits the source integer type can hold.

戻り値: The SQL type name.

GetSqlTypeName

public string GetSqlTypeName(Type clrType, int maxLength)

result = iSqlDialect.GetSqlTypeName(clrType, maxLength)

Canonical SQL type name with length applied. Dialects override when the type differs by length (e.g. PostgreSQL TEXT vs VARCHAR(N)).

GetSqlTypeName

public string GetSqlTypeName(Type clrType)

result = iSqlDialect.GetSqlTypeName(clrType)

Returns the SQL type name for a CLR type.

GetStoredMaxLength

public int GetStoredMaxLength(Type clrType, int maxLength)

result = iSqlDialect.GetStoredMaxLength(clrType, maxLength)

The length the database reports for a column created with the declared length: -1 when the dialect stores it unbounded, as SQL Server does past NVARCHAR(4000) and VARBINARY(8000).

NewId

public string NewId()

result = iSqlDialect.NewId()

Generates a new unique identifier.

NormalizeDbType

public string NormalizeDbType(string dbTypeName)

result = iSqlDialect.NormalizeDbType(dbTypeName)

Normalises a raw database type name to the canonical form used by this dialect.

Now

public string Now()

result = iSqlDialect.Now()

Current local date/time.

PrepareParameter

public void PrepareParameter(DbParameter parameter)

iSqlDialect.PrepareParameter(parameter)

Final-stage massaging of a fully populated DbParameter before it leaves the ORM layer. Lets a dialect adjust provider-specific type metadata that the generic DbType hint can't express — e.g. PostgreSQL needs timestamptz binding for UTC-kind DateTime values, which only Npgsql's own NpgsqlDbType property can express. Default is a no-op.

QuoteIdentifier

public string QuoteIdentifier(string identifier)

result = iSqlDialect.QuoteIdentifier(identifier)

Quotes an identifier (table name, column name).

ReadDbCompressionsAsync

public Task<IReadOnlyList<DbTableCompressionInfo>> ReadDbCompressionsAsync(DbConnection connection, string tableSchema, CancellationToken cancellationToken)

result = iSqlDialect.ReadDbCompressionsAsync(connection, tableSchema, cancellationToken)

Reads how each table is packed on disk. Databases without the concept report every table as None, which matches an entity that declares nothing.

connection

An open database connection.

tableSchema

Schema name; dialect default when .

cancellationToken

Cancellation token.

戻り値: One row per table.

ReadDbForeignKeysAsync

public Task<IReadOnlyList<DbForeignKeyInfo>> ReadDbForeignKeysAsync(DbConnection connection, string tableSchema, CancellationToken cancellationToken)

result = iSqlDialect.ReadDbForeignKeysAsync(connection, tableSchema, cancellationToken)

Reads foreign-key metadata from a live database. Used by the schema migrator to detect missing/extra FK constraints on tables that already exist.

connection

An open database connection.

tableSchema

Schema name (e.g. "dbo" or "public"); dialect default when .

cancellationToken

Cancellation token.

戻り値: One row per FK column — compound FKs surface as multiple rows.

ReadDbIndexesAsync

public Task<IReadOnlyList<DbIndexInfo>> ReadDbIndexesAsync(DbConnection connection, string tableSchema, CancellationToken cancellationToken)

result = iSqlDialect.ReadDbIndexesAsync(connection, tableSchema, cancellationToken)

Reads index metadata from a live database. Used by the schema migrator to detect missing entity-declared [Index] / [Unique] attributes on tables that already exist. Composite indexes are returned as multiple rows sharing IndexName with ascending ColumnOrdinal.

connection

An open database connection.

tableSchema

Schema name (e.g. "dbo" or "public"); dialect default when .

cancellationToken

Cancellation token.

戻り値: One row per indexed column — composite indexes surface as multiple rows.

ReadDbSchemaAsync

public Task<IReadOnlyList<DbColumnInfo>> ReadDbSchemaAsync(DbConnection connection, string tableSchema, CancellationToken cancellationToken)

result = iSqlDialect.ReadDbSchemaAsync(connection, tableSchema, cancellationToken)

Reads column metadata from a live database.

SysNow

public string SysNow()

result = iSqlDialect.SysNow()

System local date/time with offset.

SysUtcNow

public string SysUtcNow()

result = iSqlDialect.SysUtcNow()

System UTC date/time with offset.

UtcNow

public string UtcNow()

result = iSqlDialect.UtcNow()

Current UTC date/time.