sql语句子查询，为什么没成

Question

 string dbPath = @"D:\历年高考分数.db";
            string sq = @"Data Source=" + dbPath;
            m = new SQLiteConnection(sq);
            m.Open();
            SQLiteDataAdapter mAdapter = new SQLiteDataAdapter("select ('select yxlc,gzl from 表1 where gzl=('a'+'b'+'c')',m) from 表2",m);

a = comboBox1.Text;
b = comboBox2.Text;
c = comboBox3.Text;（下拉框选的内容）

                    图一是表1的内容，图二是表2的内容，图三是出错的地方

Answer 1

SQLiteDataAdapter mAdapter = new SQLiteDataAdapter("select ('select gzl from 表1 where gzl=('" + s + "')'),yxlc from 表2", m); string s = a + b + c;