Question

首先，如果这不是这类问题的地方，请告诉我，我会将其删除。

好的，所以我有一个MySQL PHP查询翻译类，可以转换为其他数据库中的MSSQL。以下测试文件生成以下结果（启用调试）

Test_File.php

include 'session_handler.php';
include 'database_connection.php';
$result = $db->query("SELECT * FROM industries LIMIT 5");

MySQL结果：

Query time was 0.00622892379761 seconds for:
SELECT * FROM industries LIMIT 5
Query time was 0.000350952148438 seconds for:
SELECT "session_id" FROM "sessions" WHERE "session_id" = '58'
Query time was 0.000293016433716 seconds for:
UPDATE "sessions" SET "value" = 'x', "expiration" = '0' WHERE "session_id" = '58'
Total query time: 0.00848698616028 seconds

MSSQL结果

    Query time was 0.21740579605103 seconds for:
SELECT
                c.table_schema AS "schema",
                c.table_name   AS "table",                      
                c.column_name  AS "column",
                c.data_type    AS "type"
        FROM
                INFORMATION_SCHEMA.COLUMNS AS c
        WHERE
                (c.data_type = 'nvarchar' OR
                 c.data_type = 'ntext' OR
                 c.data_type = 'nchar') AND
                c.table_catalog = DB_NAME()
        ORDER BY
                lower(c.table_name) ASC,
                lower(c.column_name) ASC
Query time was 0.21066212654114 seconds for:
SELECT TOP 5 *, CAST("industries"."industry" AS VARBINARY(MAX)) AS fmssqln__industry FROM industries
Query time was 0.21116590499878 seconds for:
SELECT "session_id" FROM "sessions" WHERE "session_id" = '58'
Query time was 0.21582698822021 seconds for:
UPDATE "sessions" SET "value" = x, "expiration" = '0' WHERE "session_id" = '58'
Total query time: 1.7053256034851 seconds

正如您所看到的，MySQL查询非常快，而转换后的查询（由类转换）需要将近2秒。

我对MSSQL的语法一无所知，所以我不确定转换的查询是否尽可能优化？

所以我的问题是 - 转换后的MSSQL查询是否是MySQL查询的正确翻译，我应该从哪里开始解决速度问题？

其他信息： MSSQL和MySQL数据库和表是完全相同的，内容和模式。

由于

Answer 1

可能是PHP正在使用的驱动程序？也许SQL Server只是速度慢。你在用Express吗？它对可以使用的资源有限制。尝试SSMS中的查询并将其粘贴在顶部以获取查询时间：

SET STATISTICS TIME ON

Express的限制是listed here。因此，CPU是1个插槽，或4个内核（可能更少），RAM限制为1GB。

MySQL到MSSQL PHP查询转换和速度的故障排除

1 个答案: