如何过滤包含列数据库中指定的所有单词的记录

Question

我知道如何使用 LIKE 运算符和 WHERE 子句在数据库的列中搜索指定的模式。例如"SELECT * From customer WHERE nam like '%" & txts & "%'"。如果 txts 包含“The boy”。显示“这孩子很好”、“这孩子怎么了”等记录。但是，我想要的是，如果 txts 包含“男孩”，它还应该显示“女孩和两个男孩在那里”，“经理带着男孩来了”之类的记录。我可以使用什么 syntax/code 来实现这一目标？

Answer 1

However, what I want is that if the txts contains "the boy", it should also display records like "the girl and two boys are there", "the manager came with a boy". What syntax/code can I used to achieve this?

类似于：

Dim search = "the boy"
search = "%" & search.Replace(" ", "%") & "%"

Dim sqlDa = New SQLiteDataAdapter("SELECT * From customer WHERE nam like :n", "your connection string here")
sqlDa.SelectCommand.Parameters.Add("n", SQLiteType.Text, search.Length, search)

Dim dt as New DataTable
sqlDa.Fill(dt)

关键部分是将搜索词从 "the boy" 修改为 "%the%boy%"，但我还提供了一个如何使用参数化查询的示例。总是（总是总是）使用参数化查询。永远（永远）没有理由不使用它们。

SQL Injection guide

SQL Injection consequences

既然我们已经澄清了问题，您可以继续修改此技术：

Dim search = "the boy"

Dim sqlDa = New SQLiteDataAdapter("SELECT * From customer WHERE 1=1 ", "your connection string here")

Dim terms = search.Split()

For i = 0 to UBound(terms)
  Dim term = terms(i)

  sqlDA.SelectCommand.CommandText &= $" AND name LIKE :n{i}"
  sqlDa.SelectCommand.Parameters.Add("n" & i, SQLiteType.Text, term.Length + 2, "%" & term & "%")

Next i


Dim dt as New DataTable
sqlDa.Fill(dt)

它只是建立一个 SQL 像：

SELECT * From customer WHERE 1=1 AND nam LIKE :n0 AND nam LIKE :n1
'n0 = %the%
'n1 = %boy%

或者我们可以使用全文搜索；设置和保持最新有点麻烦（看看 https://hackernoon.com/sqlite-the-unknown-feature-edfa73a6f022 之类的东西）——你基本上创建了一个 FTS5 虚拟 table 来跟踪你的真实 table nam/id 并使用触发器使其保持最新，然后您可以像这样查询它：

Dim search = "the boy"

Dim sqlDa = New SQLiteDataAdapter("SELECT * From customer JOIN fts_customer ON customer.id = fts_customer.id WHERE fts_customer.nam MATCH :s"
sqlDa.SelectCommand.Parameters.Add("s", SQLiteType.Text, search.Length, search)

Dim dt as New DataTable
sqlDa.Fill(dt)

请注意 System.Data.Sqlite 默认情况下似乎没有启用 FTS（您可能会收到“没有这样的模块：fts5”错误）- Microsoft.Data.Sqlite 有，但它没有一个 DataAdapter（因此您可能需要切换到 DataTable.Load(sqliteCommand.ExecuteReader()) 工作方式

Answer 2

我就是这样解决的

Dim search = "the boy"
   Using sqlconn As New SQLiteConnection(connectionString)
                Dim readN As String = "SELECT id From customer WHERE 1=1 "
                Dim cmd As New SQLiteCommand(readN, sqlconn)
                Dim terms = search.Split()
                For i = 0 To UBound(terms)
                    Dim term = terms(i)
                    cmd.CommandText &= $" AND name LIKE :n{i}"
                    cmd.Parameters.AddWithValue(":n" & i, "%" & term & "%")
                Next i
                sqlconn.Open()
                Dim reader As SQLiteDataReader = cmd.ExecuteReader
                While reader.Read
                    For i = 0 To reader.FieldCount - 1
                        MsgBox(reader.GetValue(i))
                    Next
                End While
                sqlconn.Close()
            End Using

如何过滤包含列数据库中指定的所有单词的记录

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