1：分页查询

Sql Server：

<bind name="startRow" value="(page - 1) * limit + 1"/>
<bind name="endRow" value="page * limit"/>
SELECT *
    FROM (
        SELECT ROW_NUMBER() OVER (
        <if test="sortZd!= null and sortZd!= ''">
            ORDER BY ${sortZd}
            <if test="sort!= null and sort!= ''">
                ${sort}
            </if>
        </if>
        <!-- 默认排序 -->
        <if test="sortZd == null or sortZd == ''">
            ORDER BY jy.JYSJ
        </if>
    ) AS RowNum,
        <!-- 具体的查询sql -->
) AS PagedResults
WHERE RowNum BETWEEN #{startRow} AND #{endRow}

分页Count查询：

SELECT COUNT(*) AS total_count
FROM ( 
    <!-- 具体的查询sql -->
) subquery;

Oracle：

<bind name="startRow" value="(page - 1) * limit + 1"/>
<bind name="endRow" value="page * limit"/>
SELECT * FROM (
        SELECT inn.*, ROWNUM AS rn FROM (
            SELECT * FROM ( 

            ) a
        <!-- 动态排序逻辑（if标签实现） -->
        <if test="sortZd != null and sortZd != ''">
            ORDER BY ${sortZd} 
            <if test="sort != null and sort != ''">
                ${sort}
            </if>
        </if>
        <!-- 默认排序 -->
        <if test="(sortZd == null or sortZd == '') and sort == null">
            ORDER BY FYSJ DESC
        </if>
        ) inn
        WHERE ROWNUM &lt;= #{endRow}
    )
WHERE rn &gt;= #{startRow}

分页Count查询：

SELECT COUNT(*) AS total_count
FROM ( 
    
) subquery

达梦：

<bind name="startRow" value="(page - 1) * limit"/>
        <bind name="endRow" value="limit"/>
        SELECT * FROM (

            ) a
            <if test="sortZd != null and sortZd != ''">
                ORDER BY ${sortZd}
                <if test="sort != null and sort != ''">
                    ${sort}
                </if>
            </if>
            <if test="sortZd == null or sortZd == ''">
                ORDER BY BATJ_XGRZ.xgsj DESC
            </if>
OFFSET #{startRow} ROWS FETCH FIRST #{endRow} ROWS ONLY

分页Count查询：

SELECT COUNT(*) AS total_count
FROM ( 
    
) subquery

mysql：

SELECT * FROM table<br>ORDER BY col<br>LIMIT 10 OFFSET 10;

2：时间处理

功能	Oracle	SQL Server	达梦	MySQL
日期格式化	TO_CHAR(date, 'YYYY-MM-DD')	CONVERT(VARCHAR, date, 23)	TO_CHAR(date, 'YYYY-MM-DD')	DATE_FORMAT(date, '%Y-%m-%d')
当前日期时间	SYSDATE	GETDATE()	SYSDATE	NOW()
日期加减	date + INTERVAL '1' DAY	DATEADD(DAY, 1, date)	date + INTERVAL '1' DAY	date + INTERVAL 1 DAY

Oracle：

BETWEEN TO_DATE(#{start}, 'YYYY-MM-DD') AND TO_DATE(#{end}, 'YYYY-MM-DD')

TO_DATE(#{begDate}, 'YYYY-MM-DD')

TO_DATE(#{endDate}, 'YYYY-MM-DD')

TO_CHAR(DateColumn, 'YYYY-MM-DD') AS FormattedDate

Sql server：

CONVERT(VARCHAR(10), DateColumn, 23) AS FormattedDate

  CYRQ >= #{paramMap.begdate}
        AND CYRQ < #{paramMap.plusDays}

达梦：

3：模糊查询

sqlserver:

<if test="dto.keyword != null and dto.keyword != ''">
                AND (SRM1 LIKE #{dto.keyword} + '%'
                OR MDMM LIKE '%' + #{dto.keyword} + '%'
                OR MBZM10 LIKE #{dto.keyword} + '%')
            </if>

oracle:

<if test="dto.keyword != null and dto.keyword != ''">
                AND (SRM1 LIKE #{dto.keyword} || '%'
                OR MDMM LIKE '%' || #{dto.keyword} || '%'
                OR MBZM10 LIKE #{dto.keyword} || '%')
            </if>

3：函数和语法差异

功能	Oracle	SQL Server	达梦	MySQL
空值处理	NVL(col, default)	ISNULL(col, default)	NVL(col, default)	IFNULL(col, default)
条件表达式	DECODE(col, val1, res1, res2)	CASE WHEN col=val1 THEN res1...	DECODE() 或 CASE	CASE WHEN...
自增主键	SEQUENCE + TRIGGER	IDENTITY(1,1)	IDENTITY 或 SEQUENCE	AUTO_INCREMENT
注释	-- 单行 / /* 多行 */	同上	同上	同上