--disable_query_log
set @@session.explicit_defaults_for_timestamp=off;
--enable_query_log

--disable_abort_on_error
--disable_warnings

select length('ab');
select length('ab ');
select length('ab\t');
select length('ab\0');
#特殊处理
select length('\_');
select length('\%');
#转义字符
select length('\\');
select length('\z');
select length('\n\t\r\b\0\_\%\\');
#直接忽略'\'
select length('\a');
select length('\m');
#数字转换
select length(12.466);
select length(4334);
select length(0.00);
#根据collation判断
select length('好');

#作为列名
select length(13bd);
select length(db24);

###带小数点且以0结尾
select length(00.000);
select length(00.000);
select length(1.00000);
select length(10000.10);


create database if not exists db1;
use db1;
--disable_warnings
drop table if exists utf,tx,gbk;
--enable_warnings

create table utf(c1 int primary key, c2 char(10)) collate 'utf8mb4_bin';
insert into utf values(1, '好');
select length(c2) from utf;

create table tx(s int(255) zerofill);
insert into tx values (2);
select * from tx;
select * from tx;
select * from tx;
select length(s) from tx;

drop table tx;
create table tx(s int(121) zerofill);
insert into tx values (1234);
select * from tx;
select * from tx;
select * from tx;
select length(s) from tx;

drop table tx;

#create table gbk(c1 int primary key, c2 char(10)) collate 'gbk_bin';
#insert into gbk values (1, '好');
#select length(c2) from gbk;
drop database db1;