mysql> create table t4(c int, c2 char(30), c3 varchar(21812)) charset=utf8; Query OK, 0 rows affected (0.05 sec) mysql> 1. 2. 3. 4. mysql> create table t5(c int, c2 char(30), c3 varchar(21813)) charset=utf8; ERROR 1118 (42000): Row size too large. The maximum row si...
create table t4(c int, c2 char(30), c3 varchar(N)) charset=utf8; 则此处N的最大值为 (65535-1-2-4-30*3)/3=21812 减1和减2与上例相同; 减4的原因是int类型的c占4个字节; 减30*3的原因是char(30)占用90个字节,编码是utf8。 如果被varchar超过上述的b规则,被强转成text类型,则每个字段占...
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13> Action<T1,T2,T3,T4...
CREATE TABLE t1 ( id INT NOT NULL, name CHAR(30) NOT NULL, UNIQUE INDEX UniqIdx(id) ); 1. 2. 3. 4. 5. 6. 解释:对id字段使用了索引,并且索引名字为UniqIdx。 要查看其中查询时使用的索引,必须先往表中插入数据,然后再查询数据,不然查找一个没有的id值,是不会使用索引的。(?原因:原因是所...
创建表的不同 create table t1(id int) engine=myisam; create table t2(id int) engine=innodb; create table t3(id int) engine=memory; create table t4(id int) engine=blackhole; """ MyISAM会创建三个文件 .frm 表结构文件 .MYD 表数据文件 .MYI 表索引文件(索引是用来加快数据查询的) InnoDB会...
動作<T1,T2,T3,T4,T5,T6,T7,T8,T9> 動作<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10> 動作<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11> 動作<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12> 動作<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13> 動作<T1,T2,T3,T4,T5,T6,...
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13> Action<T1,T2,T3,T4...
struct函数设有定义:struct {char mark[12];int num1;double num2;} t1,t2;,若变量均已正确赋初值,则以下语句中错误的是A)t1=t2; B)t2.num1=t1.num1; C)t2.mark=t1.mark; D)t2.num2=t1.num2;求解释,感谢啊
Action<T1,T2,T3,T4,T5,T6,T7,T8,T9> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12,T13> Action<T1,T2,T3,T4...
Action<T1,T2,T3,T4,T5,T6,T7,T8> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T10,T11,T12> Action<T1,T2,T3,T4,T5,T6,T7,T8,T9,T1...