Bagaimana untuk Meniru Fungsi LISTAGG Oracle dalam Pelayan SQL?

Mensimulasikan fungsi LISTAGG Oracle dalam SQL Server

SQL Server sendiri tidak mengandungi fungsi LISTAGG, tetapi fungsi yang serupa boleh dicapai melalui pelbagai kaedah.

MySQL

<code class="language-sql">SELECT
  FieldA,
  GROUP_CONCAT(FieldB ORDER BY FieldB SEPARATOR ',') AS FieldBs
FROM
  TableName
GROUP BY
  FieldA
ORDER BY
  FieldA;</code>

Oracle & DB2

<code class="language-sql">SELECT
  FieldA,
  LISTAGG(FieldB, ',') WITHIN GROUP (ORDER BY FieldB) AS FieldBs
FROM
  TableName
GROUP BY
  FieldA
ORDER BY
  FieldA;</code>

PostgreSQL

<code class="language-sql">SELECT
  FieldA,
  STRING_AGG(FieldB, ',' ORDER BY FieldB) AS FieldBs
FROM
  TableName
GROUP BY
  FieldA
ORDER BY
  FieldA;</code>

SQL Server

SQL Server >= 2017 & Azure SQL

<code class="language-sql">SELECT
  FieldA,
  STRING_AGG(FieldB, ',') WITHIN GROUP (ORDER BY FieldB) AS FieldBs
FROM
  TableName
GROUP BY
  FieldA
ORDER BY
  FieldA;</code>

SQL Server (versi lain)

Untuk kebolehbacaan dan kebolehselenggaraan kod, ungkapan jadual biasa (CTE) digunakan di sini:

<code class="language-sql">WITH CTE_TableName AS (
  SELECT
    FieldA,
    FieldB
  FROM
    TableName
)
SELECT
  t0.FieldA,
  STUFF(
    (
      SELECT
        ',' + t1.FieldB
      FROM
        CTE_TableName t1
      WHERE
        t1.FieldA = t0.FieldA
      ORDER BY
        t1.FieldB
      FOR XML PATH('')
    ),
    1,
    LEN(','),
    ''
  ) AS FieldBs
FROM
  CTE_TableName t0
GROUP BY
  t0.FieldA
ORDER BY
  FieldA;</code>

SQLite

Apabila pengisihan diperlukan, anda perlu menggunakan CTE atau subquery

<code class="language-sql">WITH CTE_TableName AS (
  SELECT
    FieldA,
    FieldB
  FROM
    TableName
  ORDER BY
    FieldA,
    FieldB
)
SELECT
  FieldA,
  GROUP_CONCAT(FieldB, ',') AS FieldBs
FROM
  CTE_TableName
GROUP BY
  FieldA
ORDER BY
  FieldA;</code>

Apabila tiada pengisihan diperlukan

<code class="language-sql">SELECT
  FieldA,
  GROUP_CONCAT(FieldB, ',') AS FieldBs
FROM
  TableName
GROUP BY
  FieldA
ORDER BY
  FieldA;</code>

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