正则表达式将 sql LIMIT 语法转换为 Sql Server TOP 语法

Question

我有一些为 PostgreSQL 编写的查询字符串，我必须将它们转换为 SqlServer。我正在使用 C# 6。

为了将 LIMIT 语法转换为 TOP 语法，我编写了以下简单的正则表达式：

SELECT ([\S\s]*)LIMIT (\d+) -> SELECT TOP

完整的行代码为：

return Regex.Replace(query, @"SELECT ([\S\s]*)LIMIT (\d+)", "SELECT TOP  ", RegexOptions.RightToLeft);

现在，一切都适用于简单查询，但不适用于子查询：TOP 字符串每次都放在超级父查询中。

例如尝试以下查询：

SELECT b3.aaa,
       b3.count
FROM
(
    SELECT CONCAT(b.foo / 100.0, '-', (b.foo + 10) / 100.0) AS aaa,
                      COUNT(b.foo) AS count
    FROM
    (
        SELECT b2.foo - (b2.foo % 10) AS foo
        FROM
        (
            SELECT CAST(b.foo * 100 AS INT) AS foo
            FROM eee b
                 INNER JOIN bar f ON b.bar_id = f.id
            WHERE b.foo < 1
                  AND f.nome = 'aaa'
        ) b2
    ) b
    GROUP BY b.foo
    ORDER BY b.foo
    LIMIT 10
)

转换为：

SELECT TOP 10 b3.aaa,
       b3.count
FROM
(
    SELECT CONCAT(b.foo / 100.0, '-', (b.foo + 10) / 100.0) AS aaa,
                      COUNT(b.foo) AS count
    FROM
    (
        SELECT b2.foo - (b2.foo % 10) AS foo
        FROM
        (
            SELECT CAST(b.foo * 100 AS INT) AS foo
            FROM eee b
                 INNER JOIN bar f ON b.bar_id = f.id
            WHERE b.foo < 1
                  AND f.nome = 'aaa'
        ) b2
    ) b
    GROUP BY b.foo
    ORDER BY b.foo
)

虽然我想要

SELECT b3.aaa,
       b3.count
FROM
(
    SELECT TOP 10 CONCAT(b.foo / 100.0, '-', (b.foo + 10) / 100.0) AS aaa,
                      COUNT(b.foo) AS count
    FROM
    (
        SELECT b2.foo - (b2.foo % 10) AS foo
        FROM
        (
            SELECT CAST(b.foo * 100 AS INT) AS foo
            FROM eee b
                 INNER JOIN bar f ON b.bar_id = f.id
            WHERE b.foo < 1
                  AND f.nome = 'aaa'
        ) b2
    ) b
    GROUP BY b.foo
    ORDER BY b.foo
)

我应该如何编写我需要的正则表达式？

Answer 1

我为处理引用的括号所做的一些更改可以正常工作：

var pattern = @"SELECT ((?:[^'()]|(?>'[^']+')|(?<open>\()|(?<-open>\)))+(?(open)(?!)))LIMIT (\d+)";

query = Regex.Replace(query, pattern, "SELECT TOP  ");

正则表达式将 sql LIMIT 语法转换为 Sql Server TOP 语法

Regexp convert sql LIMIT syntax to SqlServer TOP syntax

c#

regex

sql-server

postgresql

regex-greedy