protected override Expression VisitSelect(SelectExpression selectExpression)
{
IDisposable subQueryIndent = null;
if (selectExpression.Alias != null)
{
_relationalCommandBuilder.AppendLine("(");
subQueryIndent = _relationalCommandBuilder.Indent();
}
if (selectExpression.IsSetOperation)
{
GenerateSetOperation(selectExpression);
}
else
{
GenerateSelect(selectExpression);
}
if (selectExpression.Alias != null)
{
subQueryIndent.Dispose();
_relationalCommandBuilder.AppendLine()
.Append(") AS " + _sqlGenerationHelper.DelimitIdentifier(selectExpression.Alias));
}
return(selectExpression);
}
/// <summary>
/// Visit conditional
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
protected override Expression VisitConditional(ConditionalExpression expression)
{
Check.NotNull(expression, nameof(expression));
// Boolean valid return type in Cypher otherwise use case
if (expression.Type == typeof(bool))
{
Visit(expression.Test);
}
else
{
_commandBuilder.AppendLine("CASE");
using (_commandBuilder.Indent()) {
_commandBuilder.Append("WHEN ");
Visit(expression.Test);
_commandBuilder.AppendLine();
_commandBuilder.Append("THEN ");
// when true is bool or other
if (expression.IfTrue.RemoveConvert() is ConstantExpression constantIfTrue &&
!(constantIfTrue.Value is null) &&
constantIfTrue.Type.UnwrapNullableType() == typeof(bool))
{
_commandBuilder.Append(
(bool)constantIfTrue.Value
? TypedTrueLiteral
: TypedFalseLiteral
);
}
protected override Expression VisitSelect(SelectExpression selectExpression)
{
Check.NotNull(selectExpression, nameof(selectExpression));
if (IsNonComposedSetOperation(selectExpression))
{
// Naked set operation
GenerateSetOperation((SetOperationBase)selectExpression.Tables[0]);
return(selectExpression);
}
IDisposable subQueryIndent = null;
if (selectExpression.Alias != null)
{
_relationalCommandBuilder.AppendLine("(");
subQueryIndent = _relationalCommandBuilder.Indent();
}
_relationalCommandBuilder.Append("SELECT ");
if (selectExpression.IsDistinct)
{
_relationalCommandBuilder.Append("DISTINCT ");
}
GenerateTop(selectExpression);
if (selectExpression.Projection.Any())
{
GenerateList(selectExpression.Projection, e => Visit(e));
}
else
{
_relationalCommandBuilder.Append("1");
}
if (selectExpression.Tables.Any())
{
_relationalCommandBuilder.AppendLine().Append("FROM ");
GenerateList(selectExpression.Tables, e => Visit(e), sql => sql.AppendLine());
}
else
{
GeneratePseudoFromClause();
}
if (selectExpression.Predicate != null)
{
_relationalCommandBuilder.AppendLine().Append("WHERE ");
Visit(selectExpression.Predicate);
}
if (selectExpression.GroupBy.Count > 0)
{
_relationalCommandBuilder.AppendLine().Append("GROUP BY ");
GenerateList(selectExpression.GroupBy, e => Visit(e));
}
if (selectExpression.Having != null)
{
_relationalCommandBuilder.AppendLine().Append("HAVING ");
Visit(selectExpression.Having);
}
GenerateOrderings(selectExpression);
GenerateLimitOffset(selectExpression);
if (selectExpression.Alias != null)
{
subQueryIndent.Dispose();
_relationalCommandBuilder.AppendLine()
.Append(")" + AliasSeparator + _sqlGenerationHelper.DelimitIdentifier(selectExpression.Alias));
}
return(selectExpression);
}
protected override Expression VisitSelect(SelectExpression selectExpression)
{
IDisposable subQueryIndent = null;
if (!string.IsNullOrEmpty(selectExpression.Alias))
{
_relationalCommandBuilder.AppendLine("(");
subQueryIndent = _relationalCommandBuilder.Indent();
}
_relationalCommandBuilder.Append("SELECT ");
if (selectExpression.IsDistinct)
{
_relationalCommandBuilder.Append("DISTINCT ");
}
GenerateTop(selectExpression);
if (selectExpression.Projection.Any())
{
GenerateList(selectExpression.Projection, e => Visit(e));
}
else
{
_relationalCommandBuilder.Append("1");
}
if (selectExpression.Tables.Any())
{
_relationalCommandBuilder.AppendLine()
.Append("FROM ");
GenerateList(selectExpression.Tables, e => Visit(e), sql => sql.AppendLine());
}
if (selectExpression.Predicate != null)
{
_relationalCommandBuilder.AppendLine()
.Append("WHERE ");
Visit(selectExpression.Predicate);
}
if (selectExpression.Orderings.Any())
{
var orderings = selectExpression.Orderings.ToList();
if (selectExpression.Limit == null &&
selectExpression.Offset == null)
{
orderings.RemoveAll(oe => oe.Expression is SqlConstantExpression || oe.Expression is SqlParameterExpression);
}
if (orderings.Count > 0)
{
_relationalCommandBuilder.AppendLine()
.Append("ORDER BY ");
GenerateList(orderings, e => Visit(e));
}
}
else if (selectExpression.Offset != null)
{
_relationalCommandBuilder.AppendLine()
.Append("ORDER BY (SELECT 1)");
}
GenerateLimitOffset(selectExpression);
if (!string.IsNullOrEmpty(selectExpression.Alias))
{
subQueryIndent.Dispose();
_relationalCommandBuilder.AppendLine()
.Append(") AS " + _sqlGenerationHelper.DelimitIdentifier(selectExpression.Alias));
}
return(selectExpression);
}
/// <summary> /// Starts a new indentation block, so all 'Append...' calls until the /// block is disposed will be indented one level more than the current level. /// </summary> /// <returns> The object to dispose to indicate that the indentation should go back up a level. </returns> public virtual IDisposable Indent() => _commandBuilder.Indent();
/// <summary>
/// 缩进
/// </summary>
/// <returns></returns>
public override IDisposable Indent()
{
return(_commandBuilder.Indent());
}