Postgres 在给定列上查找与条件匹配的数据库表中的所有行 [英] Postgres find all rows in database tables matching criteria on a given column

问题描述

我正在尝试编写子查询，以便在所有表中搜索名为 id 的列，并且由于有多个具有 id 列的表，因此我想添加条件，使得 id = 3119093.

I am trying to write sub-queries so that I search all tables for a column named id and since there are multiple tables with id column, I want to add the condition, so that id = 3119093.

我的尝试是:

Select * 
from information_schema.tables 
where id = '3119093' and id IN (
    Select table_name 
    from information_schema.columns 
    where column_name = 'id' );

这不起作用，所以我尝试了:

This didn't work so I tried:

Select * 
from information_schema.tables 
where table_name IN (
    Select table_name 
    from information_schema.columns 
    where column_name = 'id' and 'id' IN (
        Select * from table_name where 'id' = 3119093));

这也不是正确的方法.任何帮助，将不胜感激.谢谢！

This isn't the right way either. Any help would be appreciated. Thanks!

更难的尝试是:

CREATE OR REPLACE FUNCTION search_columns(
    needle text,
    haystack_tables name[] default '{}',
    haystack_schema name[] default '{public}'
)
RETURNS table(schemaname text, tablename text, columnname text, rowctid text)
AS $$
begin
  FOR schemaname,tablename,columnname IN
      SELECT c.table_schema,c.table_name,c.column_name
      FROM information_schema.columns c
      JOIN information_schema.tables t ON
        (t.table_name=c.table_name AND t.table_schema=c.table_schema)
      WHERE (c.table_name=ANY(haystack_tables) OR haystack_tables='{}')
        AND c.table_schema=ANY(haystack_schema)
        AND t.table_type='BASE TABLE'
        --AND c.column_name = "id"
  LOOP
    EXECUTE format('SELECT ctid FROM %I.%I WHERE cast(%I as text) like %L',
       schemaname,
       tablename,
       columnname,
       needle
    ) INTO rowctid;
    IF rowctid is not null THEN
      RETURN NEXT;
    END IF;
 END LOOP;
END;
$$ language plpgsql;

select * from search_columns('%3119093%'::varchar,'{}'::name[]) ;

唯一的问题是这段代码显示了表名和列名.然后我必须手动输入

The only problem is this code displays the table name and column name. I have to then manually enter

Select * from table_name where id = 3119093

我从上面的代码中得到了表名.

where I got the table name from the code above.

我想自动实现从表中返回行，但我不知道如何自动获取表名.

I want to automatically implement returning rows from a table but I don't know how to get the table name automatically.

推荐答案

我花时间让它为你工作.

I took the time to make it work for you.

对于初学者来说，一些关于代码内部发生了什么的信息.

For starters, some information on what is going on inside the code.

1. 函数接受两个输入参数:列名和列值
2. 它需要一个创建的类型，它将返回一组
3. 第一个循环标识具有指定为输入参数的列名的表
4. 然后它形成一个查询，该查询聚合从步骤 3 获取的每个表中与输入条件匹配的所有行，并基于 ILIKE 进行比较 - 根据您的示例
5. 仅当当前访问的表中至少有一行符合指定条件(则数组不为空)时，函数才会进入第二个循环
6. 第二个循环将匹配条件的行数组取消嵌套，并使用 RETURN NEXT rec 子句将每个元素放入函数输出中

1. function takes two input arguments: column name and column value
2. it requires a created type that it will be returning a set of
3. first loop identifies tables that have a column name specified as the input argument
4. then it forms a query which aggregates all rows that match the input condition inside every table taken from step 3 with comparison based on ILIKE - as per your example
5. function goes into the second loop only if there is at least one row in currently visited table that matches specified condition (then the array is not null)
6. second loop unnests the array of rows that match the condition and for every element it puts it in the function output with RETURN NEXT rec clause

注意事项

• 使用 LIKE 搜索效率低下 - 我建议添加另一个输入参数列类型"，并通过向 pg_catalog.pg_type 表添加连接来限制查找.

  Notes

  • Searching with LIKE is inefficient - I suggest adding another input argument "column type" and restrict it in the lookup by adding a join to pg_catalog.pg_type table.

    存在第二个循环，如果为特定表找到超过 1 行，则返回每一行.

    The second loop is there so that if more than 1 row is found for a particular table, then every row gets returned.

    如果你正在寻找其他东西，比如你需要键值对，而不仅仅是值，那么你需要扩展函数.例如，您可以从行构建 json 格式.

    If you are looking for something else, like you need key-value pairs, not just the values, then you need to extend the function. You could for example build json format from rows.

    现在，进入代码.

    CREATE TABLE tbl1 (col1 int, id int); -- does contain values
    CREATE TABLE tbl2 (col1 int, col2 int); -- doesn't contain column "id"
    CREATE TABLE tbl3 (id int, col5 int); -- doesn't contain values
    
    INSERT INTO tbl1 (col1, id)
      VALUES (1, 5), (1, 33), (1, 25);
    

    表存储数据:

    postgres=# select * From tbl1;
    
     col1 | id
    ------+----
        1 |  5
        1 | 33
        1 | 25
    (3 rows)
    

    创建类型

    CREATE TYPE sometype AS ( schemaname text, tablename text, colname text, entirerow text );
    

    功能代码

    CREATE OR REPLACE FUNCTION search_tables_for_column (
        v_column_name text
      , v_column_value text
    )
    RETURNS SETOF sometype
    LANGUAGE plpgsql
    STABLE
    AS
    $$
    DECLARE
      rec           sometype%rowtype;
      v_row_array   text[];
      rec2          record;
      arr_el        text;
    BEGIN
    FOR rec IN
      SELECT 
          nam.nspname AS schemaname
        , cls.relname AS tablename
        , att.attname AS colname
        , null::text AS entirerow
      FROM 
        pg_attribute att
        JOIN pg_class cls ON att.attrelid = cls.oid 
        JOIN pg_namespace nam ON cls.relnamespace = nam.oid 
      WHERE 
        cls.relkind = 'r'
        AND att.attname = v_column_name
    LOOP
      EXECUTE format('SELECT ARRAY_AGG(row(tablename.*)::text) FROM %I.%I AS tablename WHERE %I::text ILIKE %s',
        rec.schemaname, rec.tablename, rec.colname, quote_literal(concat('%',v_column_value,'%'))) INTO v_row_array;
      IF v_row_array is not null THEN
        FOR rec2 IN
          SELECT unnest(v_row_array) AS one_row
        LOOP
          rec.entirerow := rec2.one_row;
          RETURN NEXT rec;
        END LOOP;
      END IF;
    END LOOP;
    END
    $$;
    

    示例调用和输出

    postgres=# select * from search_tables_for_column('id','5');
    
     schemaname | tablename | colname | entirerow
    ------------+-----------+---------+-----------
     public     | tbl1      | id      | (1,5)
     public     | tbl1      | id      | (1,25)
    (2 rows)
    

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