Remove alias of sort key when PagingQueryProvider has sort key with alias and group by clause.

[pongdangx2]

Hello.

Motivation

I tried to build a batch application.

Environment

• Spring boot, Spring batch
• mysql
• kotlin

Problem

I use MySqlPagingQueryProvider like below, and Query built by this provider only works for first page query.
(Because of sort key's alias)

 provider.setSelectClause(
        """
            SELECT 
                  t1.member_id         AS member_id
                , t2.kyc_id            AS kyc_id
                , SUM(t1.balance) AS total_balance
        """.trimIndent()
        )
        provider.setFromClause(
        """
            FROM cash_history t1
             LEFT JOIN kyc t2
               ON t1.member_id = t2.member_id
        """.trimIndent()
        )
        provider.setWhereClause(
        """
            WHERE t1.balance_year_month = '202412'
                  AND kyc_id is NOT NULL
        """.trimIndent()
        )
        provider.setGroupClause("GROUP BY t1.member_id")
        provider.setSortKeys(mapOf("t1.member_id" to Order.ASCENDING))

Generated Remaining Query

SELECT *
FROM (SELECT t1.member_id         AS member_id,
             t2.kyc_id            AS kyc_id,
             SUM(t1.balance) AS total_balance
      FROM cash_history t1
               LEFT JOIN kyc t2
                         ON t1.member_id = t2.member_id
      WHERE t1.balance_year_month = '202412'
        AND kyc_id is NOT NULL
      GROUP BY t1.member_id
     ) AS MAIN_QRY
WHERE ((MAIN_QRY.member_id > ?))
ORDER BY t1.member_id ASC
LIMIT 100

This generated remaining query has order by clause with t1.memeber, and valid scope of t1 alias is in MAIN_QRY.

Solution

• Use getSortKeysWithoutAliases method for building order by clause after MAIN_QRY appended.

public static String generateLimitGroupedSqlQuery(AbstractSqlPagingQueryProvider provider, String limitClause) {
		StringBuilder sql = new StringBuilder();
		sql.append("SELECT * ");
		sql.append(" FROM (");
		sql.append("SELECT ").append(provider.getSelectClause());
		sql.append(" FROM ").append(provider.getFromClause());
		sql.append(provider.getWhereClause() == null ? "" : " WHERE " + provider.getWhereClause());
		buildGroupByClause(provider, sql);
		sql.append(") AS MAIN_QRY ");
		sql.append("WHERE ");
		buildSortConditions(provider, sql);
		sql.append(" ORDER BY ").append(buildSortClause(provider.getSortKeysWithoutAliases()));
		sql.append(" ").append(limitClause);

		return sql.toString();
	}

[hpoettker]

Thanks for the PR!

But this query would now produce a java.sql.SQLSyntaxErrorException with MySQL as f.id in the outer WHERE clause can't be resolved.

[pongdangx2]

Thank you for feedback!

I fix the issue and then regenerate pull request :)