Groovy tool to count, list or delete orphaned nodes in a database with proper FK relations

OrphanNodesTool.groovy

import groovy.sql.Sql

class OrphanNodesTool {

    Sql sql;
    String schema;
    
    Set<String> tablesTargetedByForeignKeys() {
        def query = '''\
SELECT referenced_table_name
FROM INFORMATION_SCHEMA.key_column_usage
WHERE referenced_table_schema = ?
'''
        def result = new TreeSet()
        sql.eachRow( query, [ schema ] ) { row ->
            result << row[0]
        }
        return result
    }
    
    String conditionsToFindOrphans( String tableName ) {
        List<String> conditions = []
        
        def query = '''\
SELECT referenced_column_name, column_name, table_name
FROM INFORMATION_SCHEMA.key_column_usage
WHERE referenced_table_schema = ?
    AND referenced_table_name = ?
'''
        sql.eachRow( query, [ schema, tableName ] ) { row ->
            conditions << "NOT (${tableName}.${row.referenced_column_name} IN (SELECT ${row.column_name} FROM ${row.table_name}) <=> 1)"
        }
        
        return conditions.join( '\nAND ' )
    }
    
    List<Long> listOrphanedNodes( String tableName ) {
        def query = """\
SELECT ${tableName}.${tableName}_ID
FROM ${tableName}
WHERE ${conditionsToFindOrphans(tableName)}
""".toString()
        
        def result = []
        sql.eachRow( query ) { row ->
            result << row[0]
        }
        return result
    }
    
    void dumpOrphanedNodes( String tableName ) {
        def pks = listOrphanedNodes( tableName )
        println( String.format( "%8d %s", pks.size(), tableName ) )
        if( pks.size() < 10 ) {
            pks.each {
                println( String.format( "%16d", it as long ) )
            }
        } else {
            pks.collate( 20 ) { chunk ->
                chunk.each {
                    print( String.format( "%16d ", it as long ) )
                }
                println()
            }
        }
    }
    
    int countOrphanedNodes( String tableName ) {
        def query = """\
SELECT COUNT(*)
FROM ${tableName}
WHERE ${conditionsToFindOrphans(tableName)}
""".toString()
        
        int result;
        sql.eachRow( query ) { row ->
                result = row[0]
        }
        return result
    }
    
    int deleteOrphanedNodes( String tableName ) {
        def query = """\
DELETE
FROM ${tableName}
WHERE ${conditionsToFindOrphans(tableName)}
""".toString()
        
        int result = sql.execute( query )
        return result
    }
    
    void orphanedNodeStatistics() {
        def tableNames = tablesTargetedByForeignKeys()
        for( String tableName : tableNames ) {
            int n = countOrphanedNodes( tableName )
            println( String.format( "%8d %s", n, tableName ) )
        }
    }
}