Android Code Snippet [B4X] SQLite case insensitive searches with non-ASCII text

Erel

Administrator
Staff member
Licensed User
SQLite, without ICU extensions, doesn't include the information required to change the case of non-ASCII characters. This means that LIKE queries become case sensitive.

A possible workaround if you want the query to be case insensitive, is to expand the search term yourself with all possible permutations.

B4X:
Sub CreateCaseInsensitiveArgs (col As String, q As String, args As List) As String
    Dim sb As StringBuilder
    sb.Initialize
    For i = 0 To Power(2, q.Length) - 1
        If i > 0 Then sb.Append(" OR ")
        sb.Append(col).Append(" LIKE ?")
    Next
    CreateCaseHelper("", q.ToLowerCase, args)
    Return sb.ToString    
End Sub

Sub CreateCaseHelper (prefix As String, q As String, args As List)
    If q.Length = 0 Then
        args.Add("%" & prefix & "%")
        Return
    End If
    Dim f As String = q.SubString2(0, 1)
    CreateCaseHelper(prefix & f, q.SubString(1), args)
    CreateCaseHelper(prefix & f.ToUpperCase, q.SubString(1), args)
End Sub
Usage example:
B4X:
Sub mmSearch
    Dim args As List
    args.Initialize
    Dim likes As String = CreateCaseInsensitiveArgs("col1", "Query", args)
    Log(args)
    Dim Cursor As ResultSet = SQL.ExecQuery2("SELECT * FROM table1 WHERE " & likes, args)
    If Cursor.IsInitialized Then
        Do While Cursor.NextRow
            Log(Cursor.GetString("col1"))
        Loop
    End If
    Cursor.Close
End Sub
Full example here: https://www.b4x.com/android/forum/t...e-for-not-english-letters.122556/#post-765771

It is not suitable for long terms as the number of permutations is 2^n.
 
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