在 where 子句中动态添加 like 运算符

Question

任何人都可以解决我的问题吗？

我有一个最大长度的字符串数组。我想将所有字符串数组元素与单个 SQL 查询进行比较。我该怎么做？

string[] new = searchtext;
select Qid from questions where qdescriptions like string[0],string[1],string[2]

字符串数组长度不固定，是动态的。

例如：我的搜索字符串是 "admin login error"

然后我把它分成

admin
login
error

分三部分。我的预期结果应该包含数据库中的所有这三个字符串

像这样

Admin post this;
password change for login;
the error database;

希望你明白。结果应该在单个搜索查询中包含我的所有搜索字符串..

C#代码：

 public void searchdetails(string[] searchwords) { 
     SqlConnection con = new SqlConnection(); 
     con.ConnectionString = connection; con.Open(); 

     string[] soldesc = searchwords; 
     int i = 0; 

     if (soldesc.Length == 1) { 
        string query1 = "select Qid from Questions where Qdescription like '% " + soldesc[i] + " %'"; 
     }

     SqlCommand cmds = new SqlCommand(query1, con); cmds.ExecuteNonQuery();

Answer 1

试试这个

declare @searchtext nvarchar(max) = 'abc,def,pqr'

创建函数

 CREATE  FUNCTION [dbo].[fn_Split](@text varchar(8000), @delimiter varchar(20))
RETURNS @Strings TABLE
(   
  position int IDENTITY PRIMARY KEY,
  value varchar(8000)  
)
AS
BEGIN

DECLARE @index int
SET @index = -1

WHILE (LEN(@text) > 0)
  BEGIN 
    SET @index = CHARINDEX(@delimiter , @text) 
    IF (@index = 0) AND (LEN(@text) > 0) 
      BEGIN  
        INSERT INTO @Strings VALUES (@text)
          BREAK 
      END 
    IF (@index > 1) 
      BEGIN  
        INSERT INTO @Strings VALUES (LEFT(@text, @index - 1))  
        SET @text = RIGHT(@text, (LEN(@text) - @index)) 
      END 
    ELSE
      SET @text = RIGHT(@text, (LEN(@text) - @index))
    END
  RETURN
END

查询

select * from yourtable y inner join (select value from 
fn_split(@searchtext,',')) as split on y.qdescriptions  like '%+split.value+%'

Answer 2

您可以通过动态创建 sql 查询来做到这一点：

 string[] new = searchtext;
 String query = "select Qid from questions";

在您的应用程序中编写一个循环遍历您的搜索数组的 for 循环：伪代码传入：

For(String searchstring in new){
   if(new.indexof(searchstring) === 0){
      query += " where qdescriptions like " + searchstring;
   }
   else{
   //depending on what you want to do here use OR or AND
      query += " or qdescriptions like " + searchstring;
   }

}

result = query.execute();

注意：这是伪代码，因为您没有说明您使用的是什么编程语言等，所以我无法告诉您 for 循环的实际语法是什么样的，也无法告诉您如何保护您的查询免受攻击sql注射

您的 C# 代码应如下所示：

 public void searchdetails(string[] searchwords) { 
    SqlConnection con = new SqlConnection(); con.ConnectionString = connection; 
    con.Open(); 
    string[] soldesc = searchwords;
    string query1 =  "select Qid from Questions";
    For(int i = 0; i<soldesc.Length;i++){
       if (i == 0) { 
         query1 +=  "where Qdescription like '%" + soldesc[i] + "%'";
       }
       else{
         query1 += " AND Qdescription like '%" + soldesc[i] + "%'";
       }
    }


SqlCommand cmds = new SqlCommand(query1, con); cmds.ExecuteNonQuery();

Answer 3

在 C# 中，您可以像这样生成查询文本...

public static void Main()
{
    string final = GenerateParameters("tableName", "fieldName", new[] {"admin", "login", " error"});

    // execute query
    // final = "SELECT * FROM tableName WHERE fieldName LIKE '%admin%' OR fieldName LIKE '%login%' OR fieldName LIKE '% error%'"
}

static string GenerateParameters(string tableName, string fieldName, IEnumerable<string> searchTerms)
{            
    string sqlParameters = string.Join(" OR ", searchTerms.Select(x => "{0} LIKE '%{1}%'".FormatWith(fieldName, x)));
    return "SELECT * FROM {0} WHERE ".FormatWith(tableName) + sqlParameters;            
}

public static class StringExtensions
{
    public static string FormatWith(this string value, params object[] args)
    {
        return String.Format(value, args);
    }
}

在 where 子句中动态添加 like 运算符

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