基于另一個表中的資料在FORLOOP中執行SnowflakeSQL查詢

在雪花中，我正在嘗試創建一個帶有 for 回圈的 SQL 腳本，該回圈將結果輸出到基于 data_type 列的新表中

我有一個名為 PROFILE_TABLE_LIST 的表，其中的列具有表名和列名，資料型別如下所示：

我目前正在嘗試使用游標執行 for 回圈，并對每一行執行查詢，以根據列型別對表進行分析，使其看起來像這樣：

最終，我想根據 data_type 運行不同的 select 陳述句，但在這個階段，我只關注計數。這是我擁有的當前回圈。但是，選擇陳述句沒有得到正確執行，因為表名作為字串傳遞，如果我使用 TABLE(tablename) 我收到語法錯誤（我在下面注釋掉了該行：

declare
    tablename string;
    column_name string;
    row_count integer;
    table_schema string;
    table_catalog string;
    name string;
    
    tmp_array ARRAY default ARRAY_CONSTRUCT();

    res resultset default (select * from PROFILE_TABLE_LIST);
    c1 cursor for res;
    rs_output RESULTSET;
begin

  for record in c1 do
    tablename := record.TABLENAME;
    column_name := record.column_name;
    table_schema := record.table_schema;
    table_catalog := record.table_catalog;
   
   
    
    tmp_array := array_append(:tmp_array, OBJECT_CONSTRUCT('tmp_tables', record.TABLENAME, 'COUNT', (SELECT COUNT(column_name) FROM tablename)));
    -- tmp_array := array_append(:tmp_array, OBJECT_CONSTRUCT('tmp_tables', record.TABLENAME, 'COUNT', (SELECT COUNT(column_name) FROM TABLE(tablename))));
 
     
    
  end for;

  rs_output := (select value:tmp_tables, value:COUNT from table(flatten(:tmp_array)));
  return table(rs_output);
end;

uj5u.com熱心網友回復：

我會構建一個 SQL 塊并在最后運行它。

使用簡單的 SELECT 作為模式來顯示構建程序的初始化，您可以從以下位置撰寫自己的動態 sql：

WITH table_list as (
    SELECT * FROM VALUES
    ('Table1', 'PLANTS', 'TEXT'),
    ('Table1', 'HEIGHT', 'FLOAT'),
    ('Table2', 'COLOR', 'TEXT'),
    ('Table2', 'SMELL', 'TEXT')
    v(tablename, column_name, data_type)
), to_rows as (
    SELECT
        tablename
        ,CASE data_type
            WHEN 'TEXT' THEN 'SELECT ''tablename'' as TABLENAME, ''column_name'' as COLUMN_NAME, ''data_type'' as DATA_TYPE, count(column_name) as count, MAX(LEN(column_name)) as max_length, null as max_value FROM tablename '
            WHEN 'FLOAT' THEN 'SELECT ''tablename'' as TABLENAME, ''column_name'' as COLUMN_NAME, ''data_type'' as DATA_TYPE, count(column_name) as count, null as max_length, MAX(column_name) as max_value FROM tablename '
        END as sql
        ,REPLACE(REPLACE(REPLACE(sql, 'data_type', data_type), 'column_name', column_name), 'tablename', tablename) as final_sql
    FROM table_list
)
SELECT
    listagg (final_sql, ' UNION ALL ') within group(order by tablename) as the_big_sql
FROM to_rows;

這使：

如果針對這些表運行：

create table table1(plants text, height float);
create table table2(color text, smell text);

insert into table1 values ('big plant', 10.1),('medium plant', 5.3),('tiny', 1.0);
insert into table2 values ('red', 'bold'), ('blue', 'weak');

給出：

But here is the dynamic answer fully written for you:

first making the TABLE with the work to be done:

CREATE TABLE PROFILE_TABLE_LIST AS 
SELECT * FROM VALUES
    ('Table1', 'PLANTS', 'TEXT'),
    ('Table1', 'HEIGHT', 'FLOAT'),
    ('Table2', 'COLOR', 'TEXT'),
    ('Table2', 'SMELL', 'TEXT')
    v(tablename, column_name, data_type);

and using the prior created "real data tables" we can use:

declare
    sql string;
    final_sql string;
    c1 cursor for (select * from PROFILE_TABLE_LIST);
    res resultset;
begin
  final_sql := '';
  
  for record in c1 do
    if(record.data_type = 'TEXT') THEN
        sql := 'SELECT '''||record.tablename||''' as TABLENAME, '''||record.column_name||''' as COLUMN_NAME, '''||record.data_type||''' as DATA_TYPE, count('||record.column_name||') as count, MAX(LEN('||record.column_name||')) as max_length, null as max_value FROM '||record.tablename||' ';
    else
        sql := 'SELECT '''||record.tablename||''' as TABLENAME, '''||record.column_name||''' as COLUMN_NAME, ''data_type'' as DATA_TYPE, count('||record.column_name||') as count, null as max_length, MAX('||record.column_name||') as max_value FROM '||record.tablename||' ';
    end if;
    if(final_sql<>'')then 
        final_sql := final_sql || ' UNION ALL ';
    end if;
    final_sql := final_sql || sql;
        
  end for;

  res := (execute immediate :final_sql);
  return table(res);
end;

gives:

標籤：sql for循环 雪花云数据平台

上一篇：將狀態添加到for回圈中的每個已處理行，其中包含帶有GoogleAppScript的if陳述句

下一篇：從python串列中提取值