PostgreSQL 函数在循环函数中动态重塑和创建表

Question

我对 Postgre 还很陌生SQL，所以请多关照。

我很确定我的问题是我混合了普通和动态 SQL。我已经阅读了relevant documentation，但我没有足够的经验来了解我哪里出了问题（希望我的问题不是更根本的问题）。

当前脚本因查询执行错误而失败：

SQL Error [42601]: ERROR: syntax error at or near "CREATE"

我打算使用此功能逆透视 >9,000 个表（用于分析目的）；幸运的是所有表都具有相同的结构。

CREATE OR REPLACE FUNCTION all_schemaTables_unpivot(_schemaName text, _tableName text)

RETURNS void AS
$BODY$

DECLARE
    _tbl record;
BEGIN
   FOR _tbl IN
      SELECT 
         quote_ident(schemaname) || '.' || quote_ident(tablename) AS fName, 
         quote_ident(tablename) AS tName
      FROM   pg_tables
      WHERE  schemaname = _schemaName
      AND    tablename LIKE _tableName
   LOOP
      EXECUTE 'CREATE TABLE ' || _tbl.tName || '_up AS
                 SELECT region_id, key AS sequential_id, value
                 FROM (SELECT row_to_json(t.*) AS line, region_id
                       FROM ' || _tbl.tName || ' AS t) AS r
                 JOIN LATERAL json_each_text(r.line) ON (key <> "region_id")';
   END LOOP;
END;
$BODY$ LANGUAGE plpgsql;

提前致谢。

Answer 1

为了让脚本正常工作，我只需要解决两件事：

我最初没有在查询连接周围设置适当的空格（感谢@KaushikNayak）
我错误地设置了我的动态变量周围的引号值（参见 'quote_ident(_tbl.newTableName)' 添加。比我更精通 PostgreSQL 的人肯定会有更简洁的方法 - 但至少它有效！

故事的寓意，有时修复正盯着你的脸，但你盯着脚本看的时间太长了！放一放，答案就明了。

CREATE OR REPLACE FUNCTION 
all_schemaTables_unpivot(_schemaName text, _tableName text)
RETURNS void AS

$BODY$
DECLARE
_tbl record;
BEGIN
FOR _tbl IN
  SELECT 
    quote_ident(schemaname) || '.' || quote_ident(tablename) AS fullNamePath,
    quote_ident(tablename) || '_up' AS newTableName
  FROM   pg_tables
  WHERE  schemaname = _schemaName
  AND    tablename LIKE _tableName
LOOP
EXECUTE 'CREATE TABLE '|| quote_ident(_tbl.newTableName) ||' AS
         SELECT region_id, key AS sequential_id, value
         FROM (SELECT row_to_json(t.*) AS line, region_id
               FROM '|| _tbl.fullNamePath ||' AS t) AS r
         JOIN LATERAL json_each_text(r.line) ON (key <> "region_id");';
END LOOP;
END;
$BODY$ LANGUAGE plpgsql;

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