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

     1  #Empty函数在MySQL里没有，是模仿Clickhouse语义的函数，只能在MO里测试
     2  
     3  #SELECT,data type
     4  drop table if exists t1;
     5  create table t1(a varchar(255),b char(255));
     6  insert into t1 values('', 'abcd');
     7  insert into t1 values('1111', '');
     8  select empty(a),empty(b) from t1;
     9  drop table t1;
    10  
    11  #NULL,data type
    12  drop table if exists t1;
    13  create table t1(a varchar(255),b char(255));
    14  insert into t1 values(NULL, NULL);
    15  select empty(a),empty(b) from t1;
    16  drop table t1;
    17  
    18