Today I wrote a stored procedure, which requires a single quotation mark before and after the string variable. It seems that simple things have left me alone for one afternoon. Finally, I understood Oracle's abnormal rules. Oracle
String connection single quotes: 1.
Single quotation marks at the beginning and end of a string are used for character string recognition. 2.
If there are multiple single quotation marks in the first and end single quotation marks, the two single quotation marks are connected and converted into a single string single quotation mark. 3.
Single quotes must appear in pairs. Otherwise, an error occurs because the string does not know which single quotes are used to end. SelectTo_char ('aaa ')FromDual;
Select''| To_char ('aaa') |
''FromDual;
Select''' | To_char ('aaa') |
''''FromDual;
Select''' | To_char ('aaa') |
''''''FromDual;
Select''' | To_char ('aaa') |
''''''''FromDual;
Select''' | ''|
''' | To_char ('aaa') |
''''''FromDual; |
