protected override SqlColumnConstraint VisitSqlColumnConstraint(SqlColumnConstraint node)
{
var op = node.Operator;
var value = node.Value;
#region 处理一些特殊的值
switch (op)
{
case SqlColumnConstraintOperator.Like:
case SqlColumnConstraintOperator.Contains:
case SqlColumnConstraintOperator.StartWith:
case SqlColumnConstraintOperator.EndWith:
//如果是空字符串的模糊对比操作，直接认为是真。
var strValue = value as string;
if (string.IsNullOrEmpty(strValue))
{
_sql.Append("1 = 1");
return(node);
}
break;
case SqlColumnConstraintOperator.In:
case SqlColumnConstraintOperator.NotIn:
//对于 In、NotIn 操作，如果传入的是空列表时，需要特殊处理：
//In(Empty) 表示 false，NotIn(Empty) 表示 true。
if (value is IEnumerable)
{
bool hasValue = false;
foreach (var item in value as IEnumerable)
{
hasValue = true;
break;
}
if (!hasValue)
{
if (op == SqlColumnConstraintOperator.In)
{
_sql.Append("0 = 1");
}
else
{
_sql.Append("1 = 1");
}
return(node);
}
}
break;
default:
break;
}
#endregion
this.AppendColumnUsage(node.Column);
//根据不同的操作符，来生成不同的_sql。
switch (op)
{
case SqlColumnConstraintOperator.Equal:
if (value == null || value == DBNull.Value)
{
_sql.Append(" IS NULL");
}
else
{
_sql.Append(" = ");
_sql.AppendParameter(value);
}
break;
case SqlColumnConstraintOperator.NotEqual:
if (value == null || value == DBNull.Value)
{
_sql.Append(" IS NOT NULL");
}
else
{
_sql.Append(" != ");
_sql.AppendParameter(value);
}
break;
case SqlColumnConstraintOperator.Greater:
_sql.Append(" > ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.GreaterEqual:
_sql.Append(" >= ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.Less:
_sql.Append(" < ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.LessEqual:
_sql.Append(" <= ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.Like:
_sql.Append(" LIKE ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.Contains:
_sql.Append(" LIKE ");
_sql.AppendParameter("%" + value + "%");
break;
case SqlColumnConstraintOperator.StartWith:
_sql.Append(" LIKE ");
_sql.AppendParameter(value + "%");
break;
case SqlColumnConstraintOperator.EndWith:
_sql.Append(" LIKE ");
_sql.AppendParameter("%" + value);
break;
case SqlColumnConstraintOperator.In:
case SqlColumnConstraintOperator.NotIn:
var opSql = op == SqlColumnConstraintOperator.In ? "IN" : "NOT IN";
_sql.Append(" ").Append(opSql).Append(" (");
if (value is IEnumerable)
{
bool first = true;
foreach (var item in value as IEnumerable)
{
if (!first)
{
_sql.Append(',');
}
_sql.AppendParameter(item);
first = false;
}
}
else if (value is SqlNode)
{
_sql.AppendLine();
this.Indent++;
this.Visit(value as SqlNode);
this.Indent--;
_sql.AppendLine();
}
_sql.Append(')');
break;
default:
throw new NotSupportedException();
}
return(node);
}
protected override SqlColumnConstraint VisitSqlColumnConstraint(SqlColumnConstraint node)
{
var op = node.Operator;
var value = node.Value;
value = this.PrepareConstraintValue(value);
#region 处理一些特殊的值
switch (op)
{
case SqlColumnConstraintOperator.Like:
case SqlColumnConstraintOperator.Contains:
case SqlColumnConstraintOperator.StartsWith:
case SqlColumnConstraintOperator.EndsWith:
//如果是空字符串的模糊对比操作，直接认为是真。
var strValue = value as string;
if (string.IsNullOrEmpty(strValue))
{
_sql.Append("1 = 1");
return(node);
}
break;
case SqlColumnConstraintOperator.NotLike:
case SqlColumnConstraintOperator.NotContains:
case SqlColumnConstraintOperator.NotStartsWith:
case SqlColumnConstraintOperator.NotEndsWith:
//如果是空字符串的模糊对比操作，直接认为是假。
var strValue2 = value as string;
if (string.IsNullOrEmpty(strValue2))
{
_sql.Append("1 != 1");
return(node);
}
break;
case SqlColumnConstraintOperator.In:
case SqlColumnConstraintOperator.NotIn:
//对于 In、NotIn 操作，如果传入的是空列表时，需要特殊处理：
//In(Empty) 表示 false，NotIn(Empty) 表示 true。
if (value is IEnumerable)
{
bool hasValue = false;
foreach (var item in value as IEnumerable)
{
hasValue = true;
break;
}
if (!hasValue)
{
if (op == SqlColumnConstraintOperator.In)
{
_sql.Append("0 = 1");
}
else
{
_sql.Append("1 = 1");
}
return(node);
}
}
break;
default:
break;
}
#endregion
this.AppendColumnUsage(node.Column);
//根据不同的操作符，来生成不同的_sql。
switch (op)
{
case SqlColumnConstraintOperator.Equal:
if (value == null || value == DBNull.Value)
{
_sql.Append(" IS NULL");
}
else
{
_sql.Append(" = ");
_sql.AppendParameter(value);
}
break;
case SqlColumnConstraintOperator.NotEqual:
if (value == null || value == DBNull.Value)
{
_sql.Append(" IS NOT NULL");
}
else
{
_sql.Append(" != ");
_sql.AppendParameter(value);
}
break;
case SqlColumnConstraintOperator.Greater:
_sql.Append(" > ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.GreaterEqual:
_sql.Append(" >= ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.Less:
_sql.Append(" < ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.LessEqual:
_sql.Append(" <= ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.Like:
_sql.Append(" LIKE ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.NotLike:
_sql.Append(" NOT LIKE ");
_sql.AppendParameter(value);
break;
case SqlColumnConstraintOperator.Contains:
_sql.Append(" LIKE ");
_sql.AppendParameter(WILDCARD_ALL + this.Escape(value) + WILDCARD_ALL);
this.AppendEscapePlause(value);
break;
case SqlColumnConstraintOperator.NotContains:
_sql.Append(" NOT LIKE ");
_sql.AppendParameter(WILDCARD_ALL + this.Escape(value) + WILDCARD_ALL);
this.AppendEscapePlause(value);
break;
case SqlColumnConstraintOperator.StartsWith:
_sql.Append(" LIKE ");
_sql.AppendParameter(this.Escape(value) + WILDCARD_ALL);
this.AppendEscapePlause(value);
break;
case SqlColumnConstraintOperator.NotStartsWith:
_sql.Append(" NOT LIKE ");
_sql.AppendParameter(this.Escape(value) + WILDCARD_ALL);
this.AppendEscapePlause(value);
break;
case SqlColumnConstraintOperator.EndsWith:
_sql.Append(" LIKE ");
_sql.AppendParameter(WILDCARD_ALL + this.Escape(value));
this.AppendEscapePlause(value);
break;
case SqlColumnConstraintOperator.NotEndsWith:
_sql.Append(" NOT LIKE ");
_sql.AppendParameter(WILDCARD_ALL + this.Escape(value));
this.AppendEscapePlause(value);
break;
case SqlColumnConstraintOperator.In:
case SqlColumnConstraintOperator.NotIn:
var opSql = op == SqlColumnConstraintOperator.In ? "IN" : "NOT IN";
_sql.Append(" ").Append(opSql).Append(" (");
if (value is IEnumerable)
{
bool first = true;
bool needDelimiter = false;
int i = 0;
foreach (var item in value as IEnumerable)
{
if (++i > this.MaxItemsInInClause)
{
throw new TooManyItemsInInClauseException();
}
if (first)
{
first = false;
needDelimiter = item is string || item is DateTime || item is Guid;
}
else
{
_sql.Append(',');
}
if (needDelimiter)
{
_sql.Append('\'').Append(item).Append('\'');
}
else
{
_sql.Append(item);
}
//由于集合中的数据可能过多，所以这里不要使用参数化的查询。
//_sql.AppendParameter(item);
}
}
else if (value is SqlNode)
{
_sql.AppendLine();
this.Indent++;
this.Visit(value as SqlNode);
this.Indent--;
_sql.AppendLine();
}
_sql.Append(')');
break;
default:
throw new NotSupportedException();
}
return(node);
}