/// <summary>
/// 初始化一个新 <see cref="SqlJoinClause" /> 实例。
/// </summary>
/// <param name="sql">SQL 生成器</param>
public SqlJoinClause(Sql sql)
{
_sql = sql;
}
static bool Is(Sql sql, string sqltype)
{
return sql != null && sql._sql != null && sql._sql.StartsWith(sqltype, StringComparison.InvariantCultureIgnoreCase);
}
private void Build(StringBuilder sb, List<object> args, Sql lhs)
{
if(!String.IsNullOrEmpty(_sql))
{
// Add SQL to the string
if(sb.Length > 0)
{
sb.Append("\n");
}
var sql = ParametersHelper.ProcessParams(_sql, _args, args);
if(Is(lhs, "WHERE ") && Is(this, "WHERE "))
sql = "AND " + sql.Substring(6);
if(Is(lhs, "ORDER BY ") && Is(this, "ORDER BY "))
sql = ", " + sql.Substring(9);
sb.Append(sql);
}
// Now do rhs
if(_rhs != null)
_rhs.Build(sb, args, this);
}
/// <summary>
/// 添加另一个 SQL 生成器到当前的 SQL 生成器
/// </summary>
/// <param name="sql">要添加的 SQL 生成器</param>
/// <returns>合并后的 SQL 生成器</returns>
public Sql Append(Sql sql)
{
if(_rhs != null)
_rhs.Append(sql);
else
_rhs = sql;
return this;
}