[Doc] modify irregular documents (like/ not like/ regexp.md) (#6572)

docs/en/sql-reference/sql-functions/string-functions/like/like.md

@@ -28,23 +28,39 @@ under the License.
 ## description
 ### syntax
 
-'BOOLEAN like(VARCHAR str, VARCHAR pattern)'
+`BOOLEAN like(VARCHAR str, VARCHAR pattern)`
 
 Perform fuzzy matching on the string str, return true if it matches, and false if it doesn't match.
 
 like match/fuzzy match, will be used in combination with % and _.
 
-'a'   // Precise matching, the same effect as `=`.
+the percent sign ('%') represents zero, one, or more characters.
+
+the underscore ('_') represents a single character.
+
+```
+'a'   // Precise matching, the same effect as `=`
 '%a'  // data ending with a
 'a%'  // data starting with a
 '%a%' // data containing a
-'_a_' // Three digits and the middle letter is a
-'_a'  // Two digits and the ending letter is a
-'a_'  // Two digits and the initial letter is a
-
+'_a_' // three digits and the middle letter is a
+'_a'  // two digits and the ending letter is a
+'a_'  // two digits and the initial letter is a
+'a__b'  // four digits, starting letter is a and ending letter is b
+```
 ## example
 
 ```
+// table test
++-------+
+| k1    |
++-------+
+| b     |
+| bb    |
+| bab   |
+| a     |
++-------+
+
 // Return the data containing a in the k1 string
 mysql> select k1 from test where k1 like '%a%';
 +-------+

docs/en/sql-reference/sql-functions/string-functions/like/not_like.md

@@ -28,23 +28,39 @@ under the License.
 ## description
 ### syntax
 
-'BOOLEAN not like(VARCHAR str, VARCHAR pattern)'
+`BOOLEAN not like(VARCHAR str, VARCHAR pattern)`
 
 Perform fuzzy matching on the string str, return false if it matches, and return true if it doesn't match.
 
 like match/fuzzy match, will be used in combination with % and _.
 
-'a'   // Precise matching, the same effect as `=`.
+the percent sign ('%') represents zero, one, or more characters.
+
+the underscore ('_') represents a single character.
+
+```
+'a'   // Precise matching, the same effect as `=`
 '%a'  // data ending with a
 'a%'  // data starting with a
 '%a%' // data containing a
-'_a_' // Three digits and the middle letter is a
-'_a'  // Two digits and the ending letter is a
-'a_'  // Two digits and the initial letter is a
-
+'_a_' // three digits and the middle letter is a
+'_a'  // two digits and the ending letter is a
+'a_'  // two digits and the initial letter is a
+'a__b'  // four digits, starting letter is a and ending letter is b
+```
 ## example
 
 ```
+// table test
++-------+
+| k1    |
++-------+
+| b     |
+| bb    |
+| bab   |
+| a     |
++-------+
+
 // Return data that does not contain a in the k1 string
 mysql> select k1 from test where k1 not like '%a%';
 +-------+
@@ -59,8 +75,9 @@ mysql> select k1 from test where k1 not like 'a';
 +-------+
 | k1    |
 +-------+
-| bab   |
 | b     |
+| bb    |
+| bab   |
 +-------+
 ```
 

docs/en/sql-reference/sql-functions/string-functions/regexp/not_regexp.md

@@ -28,7 +28,7 @@ under the license.
 ## description
 ### syntax
 
-'BOOLEAN not regexp(VARCHAR str, VARCHAR pattern)'
+`BOOLEAN not regexp(VARCHAR str, VARCHAR pattern)`
 
 Perform regular matching on the string str, return false if it matches, and return true if it doesn't match. pattern is a regular expression.
 

docs/en/sql-reference/sql-functions/string-functions/regexp/regexp.md

@@ -28,7 +28,7 @@ under the License.
 ## description
 ### syntax
 
-'BOOLEAN regexp(VARCHAR str, VARCHAR pattern)'
+`BOOLEAN regexp(VARCHAR str, VARCHAR pattern)`
 
 Perform regular matching on the string str, return true if it matches, and return false if it doesn't match. pattern is a regular expression.
 

docs/en/sql-reference/sql-functions/string-functions/regexp/regexp_replace.md

@@ -28,7 +28,7 @@ under the License.
 ## description
 ### Syntax
 
-`VARCHAR regexp_replace(VARCHAR str, VARCHAR pattern, VARCHAR repl)
+`VARCHAR regexp_replace(VARCHAR str, VARCHAR pattern, VARCHAR repl)`
 
 
 Regular matching of STR strings, replacing the part hitting pattern with repl