SQL 语句详解
/* CREATE TABLE IF NOT EXISTS t_student (name text, age integer); */


 /* INSERT INTO t_student (name, age) VALUES ('xiaoming', 13); */


 /* UPDATE t_student SET age = 24 WHERE name = 'xiaoming'; */


 /* DROP TABLE IF EXISTS t_student;*/


 CREATE TABLE IF NOT EXISTS t_student (id integer PRIMARY KEY AUTOINCREMENT, name text, age integer);


 /* INSERT INTO t_student (name, age) VALUES ('xiaoming', 213); */


 /* UPDATE t_student SET age = 23 WHERE name = 'xiaoming'; */


 /* DELETE FROM t_student WHERE name = 'xiaohua'; */


 /*
 INSERT INTO t_student (name) VALUES ('xiaozhang');
 INSERT INTO t_student (name) VALUES ('xiaowang');
 INSERT INTO t_student (name) VALUES ('xiaoyi');
 INSERT INTO t_student (name) VALUES ('jack');
 INSERT INTO t_student (name) VALUES ('kitty');
 */


 /*
 INSERT INTO t_student (name ,age) VALUES ('xiaozhang', 23);
 INSERT INTO t_student (name ,age) VALUES ('jj', 23);
 INSERT INTO t_student (name ,age) VALUES ('33', 23);
 INSERT INTO t_student (name ,age) VALUES ('44', 23);
 */


 /* SELECT * FROM t_student WHERE age > 21 */


 /*
 INSERT INTO t_student (name, age) VALUES ('xiaoyi', 21);
 INSERT INTO t_student (name, age) VALUES ('xiaoyi', 22);
 INSERT INTO t_student (name, age) VALUES ('xiaoyi', 23);
 INSERT INTO t_student (name, age) VALUES ('xiaoyi', 24);
 INSERT INTO t_student (name, age) VALUES ('xiaoyi', 25);
 INSERT INTO t_student (name, age) VALUES ('xiaoyi', 26);
 */


 /* SELECT * FROM t_student t WHERE t.name = 'xiaoyi' AND t.age NOTNULL ORDER BY age DESC;*/


 /* SELECT s.age student_age, s.name student_name FROM t_student s; */


 /* SELECT age, name FROM t_student WHERE name LIKE '%xiao%';*/


 /* SELECT * FROM t_persion WHERE class = (SELECT id FROM t_class WHERE name = '二班'); */


 SELECT * FROM t_persion p, t_class c WHERE p.class = c.id AND c.name = '一班';