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

     1  select instr('aaa','a');
     2  instr(aaa, a)
     3  1
     4  select instr('aaa','ax');
     5  instr(aaa, ax)
     6  0
     7  select instr('aaa','aa');
     8  instr(aaa, aa)
     9  1
    10  select instr('aaa',1);
    11  instr(aaa, 1)
    12  0
    13  select instr('aaa','b');
    14  instr(aaa, b)
    15  0
    16  select instr(null,'a');
    17  instr(null, a)
    18  null
    19  select instr(1,null);
    20  instr(1, null)
    21  null
    22  select instr(null,null);
    23  instr(null, null)
    24  null
    25  select instr(null,'a');
    26  instr(null, a)
    27  null
    28  select instr('','啊');
    29  instr(, 啊)
    30  0
    31  select instr('','a');
    32  instr(, a)
    33  0
    34  select instr('',' ');
    35  instr(,  )
    36  0
    37  select instr('','');
    38  instr(, )
    39  1
    40  select instr('啊','');
    41  instr(啊, )
    42  1
    43  select instr('啊',' ');
    44  instr(啊,  )
    45  0
    46  select instr('啊','啊');
    47  instr(啊, 啊)
    48  1
    49  select instr('x啊','啊');
    50  instr(x啊, 啊)
    51  2
    52  select instr('x啊啦啦啦啦啦的','啦');
    53  instr(x啊啦啦啦啦啦的, 啦)
    54  3
    55  select instr('x啊啦啦啦啦啦的q','的');
    56  instr(x啊啦啦啦啦啦的q, 的)
    57  8
    58  select instr('x啊啦啦啦啦啦的q','q');
    59  instr(x啊啦啦啦啦啦的q, q)
    60  9
    61  create table t1(a varchar,b varchar);
    62  insert into t1 values('axa','x'),('abababa','qq'),('qwer','er');
    63  select instr(a,b) from t1;
    64  instr(a, b)
    65  2
    66  0
    67  3
    68  select instr(a,null) from t1;
    69  instr(a, null)
    70  null
    71  null
    72  null
    73  select instr(null,b) from t1;
    74  instr(null, b)
    75  null
    76  null
    77  null
    78  select instr('axa','x') from t1;
    79  instr(axa, x)
    80  2
    81  2
    82  2
    83  select instr(a,'qw') from t1;
    84  instr(a, qw)
    85  0
    86  0
    87  1
    88  select instr('qwer',b) from t1;
    89  instr(qwer, b)
    90  0
    91  0
    92  3
    93  insert into t1 values('','啊'),('','a'),('',' '),('',''),('啊',''),('啊',' '),('啊','啊'),('x啊','啊'),('x啊啦啦啦啦啦的','啦'),('x啊啦啦啦啦啦的q','的'),('x啊啦啦啦啦啦的q','q');
    94  select instr(a,b) from t1;
    95  instr(a, b)
    96  2
    97  0
    98  3
    99  0
   100  0
   101  0
   102  1
   103  1
   104  0
   105  1
   106  2
   107  3
   108  8
   109  9