Separate multiple SQL statements using Regex in Java

Question

Given a string that may contain one or more SQL statements separated by ";", for example:

String sql = "select * from table1 where col1 = 'abc;de'; select * from table2;";

I need to obtain in an array of strings the statements:

array[0] = "select * from table1 where col1 = 'abc;de';"
array[1] = "select * from table2;"

Note that semicolons could appear between apostrophes.

For example, using regex:

String regex = "???";  // <--- I can't figure out this one
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(sql);

What would be the regex to accomplish this?

Paul Vargas · Accepted Answer · 2015-03-03 22:32:05Z

You can try the following regular expression:

\s*;\s*(?=([^']*'[^']*')*[^']*$)

Visual Regex

Here is the example:

public static void main(String[] args) {
    String input = "select * from table1 where col1 = 'abc;de'; select * from table2;";

    System.out.println(java.util.Arrays.toString(
        input.split("\\s*;\\s*(?=([^']*'[^']*')*[^']*$)")
    )); // prints "[select * from table1 where col1 = 'abc;de', select * from table2]"

}

Explanation of the regular expression:

NODE                     EXPLANATION
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  ;                        ';'
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  (?=                      look ahead to see if there is:
--------------------------------------------------------------------------------
    (                        group and capture to \1 (0 or more times
                             (matching the most amount possible)):
--------------------------------------------------------------------------------
      [^']*                    any character except: ''' (0 or more
                               times (matching the most amount
                               possible))
--------------------------------------------------------------------------------
      '                        '\''
--------------------------------------------------------------------------------
      [^']*                    any character except: ''' (0 or more
                               times (matching the most amount
                               possible))
--------------------------------------------------------------------------------
      '                        '\''
--------------------------------------------------------------------------------
    )*                       end of \1 (NOTE: because you are using a
                             quantifier on this capture, only the
                             LAST repetition of the captured pattern
                             will be stored in \1)
--------------------------------------------------------------------------------
    [^']*                    any character except: ''' (0 or more
                             times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    $                        before an optional \n, and the end of
                             the string
--------------------------------------------------------------------------------
  )                        end of look-ahead

what if the select statement is surrounded by single quote and semicolon is surrounded by double quote? I mean how to add semicolon within double quote condition to this regex?

Benj · Accepted Answer · 2019-10-08 16:45:30Z

1

I come in a while after the battle, but if this can help someone...

The most simple way I found out is to rely on IBatis migration tool that has a batch file processing tool which internally splits the file into its statements.

Internally, in the ScriptRunner class, they use :

private static final Pattern DELIMITER_PATTERN = Pattern.compile("^\\s*((--)|(//))?\\s*(//)?\\s*@DELIMITER\\s+([^\\s]+)", 2);

answered Oct 8, 2019 at 16:45

Benj

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