protected override string SubstringStatement(PartialSqlString columnName, int startIndex, int length)
{
// Substring function doesn't work with parameters
if (length >= 0)
{
return(string.Format("substring({0} FROM {1} FOR {2})", columnName, startIndex, length));
}
else
{
return(string.Format("substring({0} FROM {1})", columnName, startIndex));
}
}
protected virtual object VisitBinary(BinaryExpression b)
{
object left, right;
var operand = BindOperant(b.NodeType); //sep= " " ??
if (operand == "AND" || operand == "OR")
{
var m = b.Left as MemberExpression;
if (m != null && m.Expression != null &&
m.Expression.NodeType == ExpressionType.Parameter)
{
left = new PartialSqlString(string.Format("{0}={1}", VisitMemberAccess(m), GetQuotedTrueValue()));
}
else
{
left = Visit(b.Left);
}
m = b.Right as MemberExpression;
if (m != null && m.Expression != null &&
m.Expression.NodeType == ExpressionType.Parameter)
{
right = new PartialSqlString(string.Format("{0}={1}", VisitMemberAccess(m), GetQuotedTrueValue()));
}
else
{
right = Visit(b.Right);
}
if (left as PartialSqlString == null && right as PartialSqlString == null)
{
var result = Expression.Lambda(b).Compile().DynamicInvoke();
return(new PartialSqlString(CreateParam(result)));
}
if (left as PartialSqlString == null)
{
left = ((bool)left) ? GetTrueExpression() : GetFalseExpression();
}
if (right as PartialSqlString == null)
{
right = ((bool)right) ? GetTrueExpression() : GetFalseExpression();
}
}
else
{
left = Visit(b.Left);
right = Visit(b.Right);
if (left as EnumMemberAccess != null && right as PartialSqlString == null)
{
var enumType = ((EnumMemberAccess)left).EnumType;
//enum value was returned by Visit(b.Right)
long numvericVal;
if (Int64.TryParse(right.ToString(), out numvericVal))
{
right = CreateParam(Enum.ToObject(enumType, numvericVal));
}
else
{
right = CreateParam(right);
}
}
else if (right as EnumMemberAccess != null && left as PartialSqlString == null)
{
var enumType = ((EnumMemberAccess)right).EnumType;
//enum value was returned by Visit(b.Left)
long numvericVal;
if (Int64.TryParse(left.ToString(), out numvericVal))
{
left = CreateParam(Enum.ToObject(enumType, numvericVal));
}
else
{
left = CreateParam(left);
}
}
else if (left as PartialSqlString == null && right as PartialSqlString == null)
{
var result = Expression.Lambda(b).Compile().DynamicInvoke();
return(result);
}
else if (left as PartialSqlString == null)
{
left = CreateParam(left);
}
else if (right as PartialSqlString == null)
{
right = CreateParam(right);
}
}
if (operand == "=" && right.ToString().Equals("null", StringComparison.InvariantCultureIgnoreCase))
{
operand = "is";
}
else if (operand == "<>" && right.ToString().Equals("null", StringComparison.InvariantCultureIgnoreCase))
{
operand = "is not";
}
switch (operand)
{
case "MOD":
case "COALESCE":
return(new PartialSqlString(string.Format("{0}({1},{2})", operand, left, right)));
default:
return(new PartialSqlString("(" + left + sep + operand + sep + right + ")"));
}
}