表 »rowtype« 缺少 FROM 子句条目

Posted 2023-03-28

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【中文标题】表 »rowtype« 缺少 FROM 子句条目【英文标题】：Missing FROM-clause entry for table »rowtype« 【发布时间】：2017-09-28 14:34:42 【问题描述】：

我目前正在用 plpgsql 语言编写一个函数来创建分区，这些分区将保存每个月的传感器数据（一个月一个分区和一个传感器）。我被这个错误困住了：

ERROR: missing FROM-clause entry for table »curr_sensor«
SQL state: 42P01
Context: SQL-Query »CREATE TABLE sensor_1_201609 (CHECK (timestamp >= date(curr_sensor.timestamp) AND timestamp < (date(curr_sensor.timestamp) + interval '1 month'))) INHERITS (sensor_fake_data)«
PL/pgSQL-Function create_partition_per_sensor_and_month() Line 20 at EXECUTE

函数如下：

CREATE OR REPLACE FUNCTION create_partition_per_sensor_and_month() RETURNS text as
$BODY$
-- declare variables
DECLARE
    loop_count integer := 0;
    curr_sensor sensor_fake_data%rowtype;
    curr_partition_limit timestamp;
    partition_table_name text;
    partition_index_timestamp_name text;
    partition_index_id_name text;
-- begin with the for loop...loop over every sensor and partition based on sensor and the timestamp
BEGIN                                                                   --replace mumber with variable
    FOR curr_sensor IN SELECT * FROM sensor_fake_data WHERE sensor_id = 1 ORDER BY timestamp ASC
    LOOP
        IF (loop_count = 0 OR curr_sensor.timestamp > curr_partition_limit) THEN
            curr_partition_limit := curr_sensor.timestamp + interval '1 month';
            partition_table_name := 'sensor_' || cast(curr_sensor.sensor_id as text) || '_' || to_char(date(curr_sensor.timestamp), 'YYYYMM');
            partition_index_timestamp_name := 'index_timestamp_' || cast(curr_sensor.sensor_id as text) || date(curr_sensor.timestamp);
            partition_index_id_name := 'index_id_' || cast(curr_sensor.sensor_id as text) || date(curr_sensor.timestamp);
            EXECUTE 'CREATE TABLE ' || partition_table_name || ' (CHECK (timestamp >= date(curr_sensor.timestamp) ' || 
                     'AND timestamp < (date(curr_sensor.timestamp) + interval ' || '''1 month''' || '))) ' ||
                     'INHERITS (sensor_fake_data)';
            -- add index to the new table
            EXECUTE format('CREATE INDEX %I ON %I (timestamp)', partition_index_timestamp_name, partition_table_name);
            EXECUTE format('CREATE INDEX %I ON %I (sensor_id)', partition_index_id_name, partition_table_name);
            EXECUTE format('INSERT INTO %I VALUES(curr_sensor.*)', partition_table_name);
        ELSE
            EXECUTE format('INSERT INTO %I VALUES(curr_sensor.*)', partition_table_name);
        END IF;
        loop_count := loop_count + 1;
    END LOOP;
END;
$BODY$

我不明白为什么缺少 FROM 子句。一般来说，我不明白错误，因为我只是想创建一个表（在第 20 行）并设置一些检查约束？

【问题讨论】：

curr_sensor 在CREATE TABLE 语句中没有声明。错误是正确的... @UsagiMiyamoto 所以我必须将curr_sensor 存储在一个变量下，以便在使用EXECUTE 关键字运行的SQL 查询中使用它？ EXECUTE语句的语句中没有声明变量。另外，我不认为INHERITS 是您在这里需要的...我会使用LIKE，根据文档：postgresql.org/docs/9.6/static/sql-createtable.html 也许您的意思是 ' (CHECK (timestamp >= date(curr_sensor.timestamp) ' 是 ' (CHECK (timestamp >= date($$'||curr_sensor.timestamp||'$$) ' 和 'AND timestamp < (date(curr_sensor.timestamp) + interval ' 相同？.. 【参考方案1】：

curr_sensor 是 plpgsql 函数内的行/记录变量（顺便说一句，缺少所需的声明 LANGUAGE plpgsql）。

但是您的EXECUTE 试图创建一个带有CHECK 约束的表，该约束引用了一个名为curr_sensor 的表，这显然不存在。也不应该。

相反，传递curr_sensor.timestamp 列的正确引用 (!) 值以连接正确的 DDL 语句。看起来很奇怪，您不会为此使用format()，而您的函数中有它用于其他更简单的命令。用它来清理它，并正确引用：

...
   EXECUTE format('CREATE TABLE %I (CHECK (timestamp >= %L AND timestamp < %L))
                   INHERITS (sensor_fake_data)'
                 , partition_table_name
                 , curr_sensor.timestamp::date
                 , (curr_sensor.timestamp + interval '1 month')::date);
...

可能还有更多的问题，我没有多看。