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fix:DB2 V10.5 不支持Nulls First|Nulls Last 语法，通过把该语法重写为case when解决

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farukonfly 2023-12-04 21:45:52 +08:00
parent 5f6697fd43
commit 4aa76995d4
1 changed files with 46 additions and 0 deletions
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46
mybatis-flex-core/src/main/java/com/mybatisflex/core/dialect/impl/DB2105Dialect.java
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@ -1,7 +1,18 @@
package com.mybatisflex.core.dialect.impl;
import static com.mybatisflex.core.constant.SqlConsts.DELIMITER;
import static com.mybatisflex.core.constant.SqlConsts.NULLS_FIRST;
import static com.mybatisflex.core.constant.SqlConsts.NULLS_LAST;
import static com.mybatisflex.core.constant.SqlConsts.ORDER_BY;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import com.mybatisflex.core.dialect.KeywordWrap;
import com.mybatisflex.core.dialect.LimitOffsetProcessor;
import com.mybatisflex.core.query.CPI;
import com.mybatisflex.core.query.QueryOrderBy;
import com.mybatisflex.core.query.QueryTable;
import com.mybatisflex.core.query.QueryWrapper;
public class DB2105Dialect extends CommonsDialectImpl {
//TODO: 根据DatabaseMetaData获取数据库厂商名和版本号
@ -13,6 +24,41 @@ public class DB2105Dialect extends CommonsDialectImpl {
super(keywordWrap, limitOffsetProcessor);
}
@Override
protected void buildOrderBySql(StringBuilder sqlBuilder, QueryWrapper queryWrapper, List<QueryTable> queryTables) {
List<QueryOrderBy> orderBys = CPI.getOrderBys(queryWrapper);
if (orderBys != null && !orderBys.isEmpty()) {
sqlBuilder.append(ORDER_BY);
int index = 0;
for (QueryOrderBy orderBy : orderBys) {
String orderBySql = orderBy.toSql(queryTables, this);
orderBySql = convertOderbySqlForDB2105(orderBySql); // 转换SQL语句
sqlBuilder.append(orderBySql);
if (index != orderBys.size() - 1) {
sqlBuilder.append(DELIMITER);
}
index++;
}
}
}
private String convertOderbySqlForDB2105(String sql) {
Pattern pattern = Pattern.compile("(\\S+)\\s+(\\S+)\\s+("+NULLS_FIRST.trim()+"|"+NULLS_LAST.trim()+")");
Matcher matcher = pattern.matcher(sql);
if (matcher.find()) {
String column = matcher.group(1);
String orderType = matcher.group(2);
String nullOrder = matcher.group(3);
if (NULLS_FIRST.trim().equals(nullOrder)) {
sql = "CASE WHEN " + column + " IS NULL THEN 0 ELSE 1 END, " + column+" "+orderType;
} else if (NULLS_LAST.trim().equals(nullOrder)) {
sql = "CASE WHEN " + column + " IS NULL THEN 1 ELSE 0 END, " + column+" "+orderType;
}
}
return sql;
}
public interface DB2105LimitOffsetProcessor {
LimitOffsetProcessor DB2105 = (dialect, sql, queryWrapper, limitRows, limitOffset) -> {
StringBuilder limitSqlFragment = new StringBuilder(