SELECT ... FOR UPDATE走的是IX锁(意向排它锁) 即在符合条件的rows上都加了排它锁,其他session也就无法在这些记录上添加任何的S锁或X锁。 如果不存在一致性非锁定读的话(读取快照),那么其他session是无法读取和修改这些记录的,但是innodb有非锁定读(快照读并不需要加锁) select ... for update仅适用于InnoDB...
mysql> insert into stu values (5,'jake',null,default); Query OK, 1 row affected (0.05 sec) 小结: default关键字用来插入默认值,null用来插入空值. 3、插入多条数据 mysql> insert into stu values (6,'李白','男','四川'),(7,'杜甫','男','湖北'); Query OK, 2 rows affected (0.00 ...
mysql>EXPLAINSELECT*FROMsakila.film_actorWHEREfilm_id=1\G***1\.row***id:1select_type:SIMPLEtable:film_actorpartitions:NULLtype:refpossible_keys:idx_fk_film_idkey:idx_fk_film_idkey_len:2ref:constrows:10filtered:100.00Extra:NULL EXPLAIN显示 MySQL 估计只需要访问 10 行。换句话说,查询优化器知...
select count(*) from tb_student; select count(all *) from tb_student; select count(all courseName) from tb_student; select max(all courseName) from tb_student; select min(all courseName) from tb_student; select sum(all courseName) from tb_student; select avg(all score) from tb_score...
SQL_CALC_FOUND_ROWS ® SQL_NO_CACHE SQL_SMALL_RESULT ® SQL_THREAD SQL_TSI_DAY SQL_TSI_HOUR SQL_TSI_MINUTE SQL_TSI_MONTH SQL_TSI_QUARTER SQL_TSI_SECOND SQL_TSI_WEEK SQL_TSI_YEAR SRID; added in 8.0.3 (nonreserved) SSL ® STACKED START STARTING ® STARTS STATS_AUTO_RECALC STAT...
set_num_rows() : Row_bunch< Column_type > set_num_rows_per_fetch() : Statement_handle set_num_tasks() : anonymous_namespace{clone0api.cc}::Fixup_data set_numa_interleave_t() : set_numa_interleave_t set_number() : dd::Partition, dd::Partition_impl set_numeric() : DTCollation ...
mysqli_result::fetch_all -- mysqli_fetch_all— Fetch all result rows as an associative array, a numeric array, or both说明 面向对象风格 public mysqli_result::fetch_all(int $mode = MYSQLI_NUM): array 过程化风格 mysqli_fetch_all(mysqli_result $result, int $mode = MYSQLI_NUM): arra...
found_rows():返回最后一个select查询语句检索的数据总行数。 cast(v as 类型):将v转换为指定的数据类型。 3.8、... 除开上述这些函数之外,其实在MySQL还有很多很多的函数,但目前几乎已经将所有常用的函数全部列出来了,因此对于其他偏冷门一些的函数就不再介绍。当然,就算你需要的某个功能在MySQL中没有提供函数...
if ($result->num_rows > 0) { while($row = $result->fetch_assoc()) { echo “字段1: ” . $row[“column1″]. ”– 字段2: ” . $row[“column2”]. “ “; } } else { echo “0 结果”; } // 关闭连接 $conn->close(); ...
insert into sbtest1(k,c,pad) select k,c,pad from sbtest1; Query OK, 1000000 rows affected ...