SELECT "hello" & "world" AS result;
-- 输出结果：helloworld

SELECT left("hello world", 5) AS result;
-- 输出结果：hello

SELECT right("hello world", 5) AS result;
-- 输出结果：world

SELECT replace("hello world", "world", "MySQL") AS result;
-- 输出结果：hello MySQL

SELECT str(123) AS result;
-- 输出结果：123

SELECT ucase("hello world") AS result;
-- 输出结果：HELLO WORLD

SELECT lcase("HELLO WORLD") AS result;
-- 输出结果：hello world

CREATE TABLE fruits (
  id INT,
  name VARCHAR(255)
);

INSERT INTO fruits (id, name) VALUES (1, 'apple'), (2, 'banana'), (3, 'orange');

SELECT GROUP_CONCAT(name) FROM fruits;
-- 输出结果：apple,banana,orange

Function CombineFields (tableName As String, fieldName As String, Optional sep As String = ",") As String
    Dim rs As DAO.Recordset
    Dim result As String

    Set rs = CurrentDb.OpenRecordset("SELECT [" & fieldName & "] FROM [" & tableName & "]")

    If Not (rs.EOF And rs.BOF) Then
        rs.MoveFirst
        Do Until rs.EOF
            If Not IsNull(rs(0)) Then
                result = result & rs(0) & sep
            End If
            rs.MoveNext
        Loop
    End If

    If Len(result) > Len(sep) Then
        result = Left(result, Len(result) - Len(sep))
    End If

    CombineFields = result
End Function

SELECT CombineFields("fruits", "name", ",") AS result;
-- 输出结果：apple,banana,orange