/// <summary>
/// 解析查询列中的字符串截取函数
/// </summary>
/// <param name="callExp"></param>
/// <param name="sqlBuilder"></param>
/// <param name="fullExpression"></param>
/// <param name="alias"></param>
private void ResolveSelectForSubstring(MethodCallExpression callExp, StringBuilder sqlBuilder, LambdaExpression fullExpression, string alias)
{
if (callExp.Object is MemberExpression objExp && objExp.Expression.NodeType == ExpressionType.Parameter)
{
var funcName = _sqlAdapter.FuncSubstring;
var colName = _queryBody.GetColumnName(objExp, fullExpression);
var start = CommonExtensions.ToInt(((ConstantExpression)callExp.Arguments[0]).Value) + 1;
if (callExp.Arguments.Count > 1)
{
var length = CommonExtensions.ToInt(((ConstantExpression)callExp.Arguments[1]).Value);
sqlBuilder.AppendFormat("{0}({1},{2},{3}) AS {4},", funcName, colName, start, length, alias);
}
else
{
if (_sqlAdapter.SqlDialect == SqlDialect.SqlServer)
{
sqlBuilder.AppendFormat("{0}({1},{2},{3}) AS {4},", funcName, colName, start, $"LEN({colName})-{start - 1}", alias);
}
else
{
sqlBuilder.AppendFormat("{0}({1},{2}) AS {3},", funcName, colName, start, alias);
}
}
}
}
/// <summary>
/// 附加值
/// </summary>
/// <param name="sqlBuilder"></param>
/// <param name="type"></param>
/// <param name="value"></param>
private void AppendValue(StringBuilder sqlBuilder, Type type, object value)
{
if (type.IsEnum || type == typeof(bool))
{
sqlBuilder.AppendFormat("{0}", CommonExtensions.ToInt(value));
}
else if (type == typeof(string) || type == typeof(char) || type == typeof(Guid))
{
sqlBuilder.AppendFormat("'{0}'", value);
}
else if (type == typeof(DateTime))
{
sqlBuilder.AppendFormat("'{0:yyyy-MM-dd HH:mm:ss}'", CommonExtensions.ToDateTime(value));
}
else
{
sqlBuilder.AppendFormat("{0}", value);
}
}
