Bug#29904751: LIKE CONDITION FOR DATE COLUMN RETURNS ERROR

Item_func_like inherits resolve_type from Item_bool_func2 but does not
have much in common with it's parent since every comparison must be done
as strings. Also the call to set_cmp_func() is unnecesary and results in
an error when comparing temporal types with strings.
This patch fixes this error by overriding resolve_type in
Item_func_like, and by omitting the call to set_cmp_func.

Change-Id: I1cea9d5fcf54f3539016aed4cdb77501a547a5ed

mysql-test/r/func_like.result

@@ -404,3 +404,16 @@ DELETE FROM t1 WHERE
 ) LIKE (c1);
 ERROR 22007: Incorrect datetime value: '42'
 DROP TABLE t1;
+#
+# Bug#29904751: LIKE CONDITION FOR DATE COLUMN RETURNS ERROR
+#
+CREATE TABLE t(col1 DATE);
+INSERT INTO t(col1) VALUES('2019-06-13'), ('2019-07-13');
+SELECT * FROM t WHERE col1 LIKE '2019%';
+col1
+2019-06-13
+2019-07-13
+SELECT * FROM t WHERE col1 LIKE '2019-06-1%';
+col1
+2019-06-13
+DROP TABLE t;

mysql-test/r/type_temporal_fractional.result

@@ -15587,11 +15587,11 @@ s1
 1000-00-01 00:00:00
 1000-00-01 00:00:00
 DROP TABLE t1;
-SELECT BINARY SYSDATE(6) LIKE '____-__-__ __:__:__.______';
-BINARY SYSDATE(6) LIKE '____-__-__ __:__:__.______'
+SELECT SYSDATE(6) LIKE '____-__-__ __:__:__.______';
+SYSDATE(6) LIKE '____-__-__ __:__:__.______'
 1
-SELECT BINARY SYSDATE(6) NOT LIKE '%.000000' || BINARY SYSDATE(6) NOT LIKE '%.000000';
-BINARY SYSDATE(6) NOT LIKE '%.000000' || BINARY SYSDATE(6) NOT LIKE '%.000000'
+SELECT SYSDATE(6) NOT LIKE '%.000000' || SYSDATE(6) NOT LIKE '%.000000';
+SYSDATE(6) NOT LIKE '%.000000' || SYSDATE(6) NOT LIKE '%.000000'
 1
 Warnings:
 Warning	1287	'|| as a synonym for OR' is deprecated and will be removed in a future release. Please use OR instead

mysql-test/t/func_like.test

@@ -316,3 +316,13 @@ DELETE FROM t1 WHERE
    (SELECT * WHERE '520:33:32.77' < (c1 - INTERVAL(1) MONTH))
 ) LIKE (c1);
 DROP TABLE t1;
+
+--echo #
+--echo # Bug#29904751: LIKE CONDITION FOR DATE COLUMN RETURNS ERROR
+--echo #
+CREATE TABLE t(col1 DATE);
+INSERT INTO t(col1) VALUES('2019-06-13'), ('2019-07-13');
+SELECT * FROM t WHERE col1 LIKE '2019%';
+SELECT * FROM t WHERE col1 LIKE '2019-06-1%';
+DROP TABLE t;
+

mysql-test/t/type_temporal_fractional.test

@@ -6231,8 +6231,8 @@ DROP TABLE t1;
 
 # SYSDATE(n) post-decimal digits are not zeros
 # Disable warnings, see Bug#61216: Incorrect warning for "datetime LIKE string"
-SELECT BINARY SYSDATE(6) LIKE '____-__-__ __:__:__.______';
-SELECT BINARY SYSDATE(6) NOT LIKE '%.000000' || BINARY SYSDATE(6) NOT LIKE '%.000000';
+SELECT SYSDATE(6) LIKE '____-__-__ __:__:__.______';
+SELECT SYSDATE(6) NOT LIKE '%.000000' || SYSDATE(6) NOT LIKE '%.000000';
 
 CREATE TABLE t1 (s1 DATETIME(2));
 INSERT INTO t1 VALUES ('1970-01-01 11:11:11.1234');

sql/item_cmpfunc.cc

@@ -639,14 +639,6 @@ bool Item_bool_func2::resolve_type(THD *thd) {
 
   args[0]->cmp_context = args[1]->cmp_context =
       item_cmp_type(args[0]->result_type(), args[1]->result_type());
-  // Make a special case of compare with fields to get nicer DATE comparisons
-
-  if (functype() == LIKE_FUNC)  // Disable conversion in case of LIKE function.
-  {
-    if (set_cmp_func()) DBUG_RETURN(true);
-
-    DBUG_RETURN(false);
-  }
 
   /*
     Geometry item cannot participate in an arithmetic or string comparison or
@@ -661,15 +653,40 @@ bool Item_bool_func2::resolve_type(THD *thd) {
       reject_geometry_args(arg_count, args, this))
     DBUG_RETURN(true);
 
+  // Make a special case of compare with fields to get nicer DATE comparisons
   if (!thd->lex->is_ps_or_view_context_analysis()) {
     bool cvt1, cvt2;
     if (convert_constant_arg(thd, args[0], &args[1], &cvt1) ||
         convert_constant_arg(thd, args[1], &args[0], &cvt2))
       DBUG_RETURN(true);
     if (cvt1 || cvt2) DBUG_RETURN(false);
   }
-  if (set_cmp_func()) DBUG_RETURN(true);
-  DBUG_RETURN(false);
+  DBUG_RETURN(set_cmp_func());
+}
+
+bool Item_func_like::resolve_type(THD *) {
+  // Function returns 0 or 1
+  max_length = 1;
+
+  /*
+    See agg_item_charsets() in item.cc for comments
+    on character set and collation aggregation.
+  */
+  if (args[0]->result_type() == STRING_RESULT &&
+      args[1]->result_type() == STRING_RESULT) {
+    if (agg_arg_charsets_for_comparison(cmp.cmp_collation, args, 2))
+      return true;
+  } else if (args[1]->result_type() == STRING_RESULT) {
+    cmp.cmp_collation = args[1]->collation;
+  } else {
+    cmp.cmp_collation = args[0]->collation;
+  }
+
+  // LIKE is always carried out as string operation
+  args[0]->cmp_context = STRING_RESULT;
+  args[1]->cmp_context = STRING_RESULT;
+
+  return false;
 }
 
 void Arg_comparator::cleanup() {
@@ -5704,15 +5721,15 @@ longlong Item_func_like::val_int() {
 
   String *res = args[0]->val_str(&cmp.value1);
   if (args[0]->null_value) {
-    null_value = 1;
+    null_value = true;
     return 0;
   }
   String *res2 = args[1]->val_str(&cmp.value2);
   if (args[1]->null_value) {
-    null_value = 1;
+    null_value = true;
     return 0;
   }
-  null_value = 0;
+  null_value = false;
   if (current_thd->is_error()) return 0;
 
   return my_wildcmp(cmp.cmp_collation.collation, res->ptr(),

sql/item_cmpfunc.h

@@ -2026,6 +2026,7 @@ class Item_func_like final : public Item_bool_func2 {
   cond_result eq_cmp_result() const override { return COND_TRUE; }
   const char *func_name() const override { return "like"; }
   bool fix_fields(THD *thd, Item **ref) override;
+  bool resolve_type(THD *) override;
   void cleanup() override;
   /**
     @retval true non default escape char specified

sql/opt_range.cc

@@ -7615,7 +7615,7 @@ static SEL_ROOT *get_mm_leaf(RANGE_OPT_PARAM *param, Item *conf_func,
     max_str = min_str + length;
     if (maybe_null) max_str[0] = min_str[0] = 0;
 
-    Item_func_like *like_func = static_cast<Item_func_like *>(param->cond);
+    Item_func_like *like_func = down_cast<Item_func_like *>(param->cond);
 
     // We can only optimize with LIKE if the escape string is known.
     if (!like_func->escape_is_evaluated()) goto end;