java - android.database.sqlite.SQLiteException : near "UNION": syntax error

Question

我正在使用适用于 Android 的 SQLite 数据库

SQLite 查询

SELECT t1.id,t1.name, t1.email FROM ((SELECT id,first_name as 
name,email FROM single_general where unique_code='UD') 
UNION ALL (SELECT name,email FROM school where 
unique_code='UD') ) t1

Answer 1

SELECT syntax复合查询不允许使用括号。删除它们，以便只留下子查询周围的括号:

SELECT id, name, email
FROM (SELECT id, first_name AS name, email
      FROM single_general
      WHERE unique_code = 'UD'
      UNION ALL
      SELECT 0, name, email
      FROM school
      WHERE unique_code = 'UD');