github.com/matrixorigin/matrixone@v1.2.0/test/distributed/cases/function/func_string_char_length.test (about)

     1  #SELECT，多种语言
     2  SELECT CHAR_LENGTH("你好");
     3  SELECT CHAR_LENGTH("français");
     4  SELECT CHAR_LENGTH("にほんご");
     5  SELECT CHAR_LENGTH("Español");
     6  
     7  #NULL
     8  SELECT CHAR_LENGTH(NULL);
     9  
    10  
    11  create table t1 (a char(20));
    12  insert into t1 values ('123456'),('андрей');
    13  select char_length(a), length(a), a from t1 order by a;
    14  drop table t1;
    15  
    16  #EXTRME VALUE
    17  select char_length('\n\t\r\b\0\_\%\\');
    18  
    19  #嵌套
    20  
    21  SELECT CHAR_LENGTH(concat_ws(" ",121,83,81,'76')) as my_column;
    22  
    23  
    24  
    25  create table t (c varchar(20));
    26  insert into t values ('\\');
    27  select char_length(c) from t;
    28  insert into t values ('0C');
    29  select sum(char_length(c)) from t;
    30  insert into t values ('"');
    31  select sum(char_length(c)) from t;
    32  insert into t values ('\a');
    33  select sum(char_length(c)) from t;
    34  insert into t values ('\b');
    35  select sum(char_length(c)) from t;
    36  insert into t values ('\t');
    37  select sum(char_length(c)) from t;
    38  insert into t values ('\n');
    39  select sum(char_length(c)) from t;
    40  insert into t values ('\r');
    41  select sum(char_length(c)) from t;
    42  insert into t values ('10');
    43  select sum(char_length(c)) from t;
    44  drop table t;
    45  
    46  
    47  
    48  #DATATYPE
    49  create table t1(a tinyint, b SMALLINT, c BIGINT, d INT, e BIGINT, f FLOAT, g DOUBLE, h decimal(38,19), i DATE, k datetime, l TIMESTAMP, m char(255), n varchar(255));
    50  insert into t1 values(1, 1, 2, 43, 5, 35.5, 31.133, 14.314, "2012-03-10",  "2012-03-12 10:03:12", "2022-03-12 13:03:12", "ab23c", "d5cf");
    51  insert into t1 values(71, 1, 2, 34, 5, 5.5, 341.13, 15.314, "2012-03-22",  "2013-03-12 10:03:12", "2032-03-12 13:04:12", "abr23c", "3dcf");
    52  insert into t1 values(1, 1, 21, 4, 54, 53.5, 431.13, 14.394, "2011-03-12",  "2015-03-12 10:03:12", "2002-03-12 13:03:12", "afbc", "dct5f");
    53  insert into t1 values(1, 71, 2, 34, 5, 5.5, 31.313, 124.314, "2012-01-12",  "2019-03-12 10:03:12", "2013-03-12 13:03:12", "3abd1c", "dcvf");
    54  select char_length(a),char_length(b),char_length(c),char_length(d),char_length(e),char_length(f),char_length(g),char_length(h),char_length(i),char_length(k),char_length(l),char_length(m),char_length(n) from t1;
    55  drop table t1;
    56  
    57  #0.5暂不支持time类型
    58  #create table t1(a time)
    59  #insert into t1 values("10:03:12");
    60  #select char_length(a) from t1;
    61  #drop table t1;
    62  
    63  
    64  #insert into, distinct
    65  create table t1(a int, b varchar(255));
    66  insert into t1 select char_length("你好"), "你好";
    67  insert into t1 select char_length("再见"), "再见";
    68  select distinct a, char_length(b) from t1;
    69  drop table t1;
    70  
    71  #WHERE
    72  drop table if exists t1;
    73  create table t1(a INT,  b varchar(255));
    74  insert into t1 select char_length("你好"), "你好";
    75  insert into t1 select char_length("再见"), "再见";
    76  select * from t1 where char_length(b)=2;
    77  drop table t1;
    78  
    79  
    80  #ON CONDITION
    81  drop table if exists t1;
    82  drop table if exists t2;
    83  create table t1(a INT,  b varchar(255));
    84  create table t2(a INT,  b varchar(255));
    85  insert into t1 select char_length("你好"), "你好";
    86  insert into t1 select char_length("再见"), "再见";
    87  insert into t2 select char_length("今天"), "日期时间";
    88  insert into t2 select char_length("明天"), "明天";
    89  SELECT t1.a, t2.a FROM t1 JOIN t2 ON (char_length(t1.b) = char_length(t2.b));
    90  drop table t1;
    91  drop table t2;
    92  
    93  #HAVING，比较操作
    94  drop table if exists t1;
    95  create table t1(a INT,  b varchar(255));
    96  insert into t1 select char_length("你好"), "你好";
    97  insert into t1 select char_length("再见"), "再见";
    98  select b from t1 group by b having char_length(b)<3;
    99  drop table t1;
   100  
   101  
   102  #算术操作
   103  SELECT char_length("你好")+char_length("再见");
   104