搜索时 SQL 查询出错

Question

搜索时 SQL 查询出错

3

我有一个 SQL 查询，可以显示数据库中不同表的信息。然后，这个查询将在 DataGrid 中显示，并且我有一些选项在 DropDownList 中，可以搜索 DataGrid 中特定的值。问题是搜索功能不能正确地显示 CollectName 或 DeliverName 的信息。 DropDownList 的代码如下：

 private static readonly Dictionary<string, string> SearchFields = new Dictionary<string, string> {
            { "Customer", "c.Name" },
            { "Department", "jn.Department" },
            { "CollectName", "SELECT Name FROM job_address WHERE AddressType = 3 AND JobID = jn.ID" },
            { "DeliverName", "(SELECT Name FROM job_address WHERE AddressType = 2 AND JobID = jn.ID)" }
        };

在这个SQL查询中，CollectName和DeliverName是内部选择语句，这就是导致问题的原因，因为对于Customer和Department的搜索工作正常。

SELECT  c.Name,
        COUNT(distinct jn.ID) as Jobs,
        sum(jn.OutTurn) as Outturn,
        SUM(jn.ActualWeight) as GrossWt,
        SUM(jn.CBM) as CBM,
        jn.Department,
        (SELECT Name FROM job_address WHERE AddressType =3 AND JobID = jn.ID) as CollectName,
        (SELECT Name FROM job_address WHERE AddressType =2 AND JobID = jn.ID) as DeliverName       
FROM customer c
LEFT JOIN job_address ja ON c.AccountCode = ja.Code AND c.Company_ID = ja.Company_ID
JOIN  AddressType jat ON ja.AddressType = jat.ID and jat.Description = 'Debtor'
LEFT JOIN job_new jn ON ja.JobID = jn.ID
WHERE c.Company_ID = ?compid
GROUP BY c.ID

我有一个搜索功能，它需要从下拉列表中选择的值和文本框中输入的值： ```html

我有一个搜索功能，它需要从下拉列表中选择的值和文本框中输入的值：

```

 List<MySqlParameter> param = new List<MySqlParameter>{ new MySqlParameter("compid", CompanyID) };
            StringBuilder SQL = new StringBuilder(SearchSQL);
            if (SearchFieldKey != null && SearchFieldKey.Length > 0)
            {
                SQL.Append(" AND (");
                for (int i = 0; i < SearchFieldKey.Length; i++)
                {
                    if (SearchFields.ContainsKey(SearchFieldKey[i]))
                    {

                        SQL.Append(SearchFields[SearchFieldKey[i]] + " LIKE ?parameter" + i.ToString());
                        param.Add(new MySqlParameter("parameter" + i.ToString(), "%" + SearchTerms[i] + "%"));

                        if (i != SearchFieldKey.Length - 1)
                            SQL.Append(" OR ");
                    }
                    else
                        throw new Exception("Error: Attempted to search on invalid field. Check SearchFields Argument.");
                }
                SQL.Append(") ");
            }

例如，当我搜索客户时，SQL查询会将以下行添加到查询语句的末尾：

WHERE c.Company_ID = ?compid AND (c.Name LIKE ?parameter0)

当我搜索CollectName或DeliverName时，查询语句如下：

WHERE c.Company_ID = ?compid AND (SELECT Name FROM job_address WHERE AddressType = 3 AND JobID = jn.ID LIKE ?parameter0)

这个SQL查询是否存在问题，导致CollectName和DeliverName无法正常工作？

- user123456789

1个回答

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- Cyril Gandon · Accepted Answer

括号不匹配，应该是：

WHERE c.Company_ID = ?compid 
AND (SELECT Name FROM job_address WHERE AddressType = 3 AND JobID = jn.ID) LIKE ?parameter0

为了解决这个问题，你可以在你的字典中嵌入以下语句：

{ "CollectName", "(SELECT Name FROM job_address WHERE AddressType = 3 AND JobID = jn.ID)" },

在构建 SQL 的方法中，可以自动嵌入子查询。

SQL.Append("(" + SearchFields[SearchFieldKey[i]] + ") LIKE ?parameter" + i.ToString());

完整更正：如果您正在使用StringBuilder，则不应尝试将字符串连接在一起。

var param = new List<MySqlParameter> { new MySqlParameter("compid", CompanyID) };
StringBuilder SQL = new StringBuilder(SearchSQL);
if (SearchFieldKey != null && SearchFieldKey.Length > 0)
{
    SQL.Append(" AND (");
    for (int i = 0; i < SearchFieldKey.Length; i++)
    {
        if (SearchFields.ContainsKey(SearchFieldKey[i]))
        {
            SQL.Append("(");
            SQL.Append(SearchFields[SearchFieldKey[i]]);
            SQL.Append(") LIKE ?parameter");
            SQL.Append(i);
            param.Add(new MySqlParameter("parameter" + i.ToString(), "%" + SearchTerms[i] + "%"));

            if (i != SearchFieldKey.Length - 1)
                SQL.Append(" OR ");
        }
        else
            throw new Exception("Error: Attempted to search on invalid field. Check SearchFields Argument.");
    }
    SQL.Append(") ");
}