Java Interview Questions On JDBC Conectivity Page5 - What are the different types of Statements? | If you want to use the percent sign (%) as the percent sign and not have it interpreted as the SQL wildcard used in SQL LIKE queries, how to do that? | How to escape ' symbol found in the input line?

20. If you want to use the percent sign (%) as the percent sign and not have it interpreted as the SQL wildcard used in SQL LIKE queries, how to do that?

Answer:

Use escape keyword. For example: stmt.executeQuery("select tax from sales where tax like '10\%' {escape '\'}");

21. How to escape ' symbol found in the input line?

Answer

You may use a method to do so:

static public String escapeLine(String s) {
String retvalue = s;
if (s.indexOf ("'") != -1 ) {
    StringBuffer hold = new StringBuffer();
    char c;
    for(int i=0; i < s.length(); i++ ) {
      if ((c=s.charAt(i)) == '\'' ) {
      hold.append ("''");
    }else {
     hold.append(c);
    }
}
retvalue = hold.toString();
}
return retvalue;
}
Note that such method can be extended to escape any other characters that the database driver may interprete another way.

22. How to make an update?

Answer

Creates a Statement object and calls the Statement.executeUpdate method.

String updateString = "INSERT INTO aDatabase VALUES (some text)";
int count = stmt.executeUpdate(updateString);