如何创建临时表或仅从循环中的列中选择不同的值

Posted 2023-03-28

【中文标题】如何创建临时表或仅从循环中的列中选择不同的值

【英文标题】：how to create a temporary table or to select only distinct values from a column in a loop

【发布时间】：2012-08-23 15:40:06

【问题描述】：

我有一个有 2 列的表，第一列有重复值，现在在 while 循环中我想一次选择每个不同的值，我在 sql 中创建了一个临时表，但是在 oracle sql developer 中我该如何编写代码？

CREATE TABLE look_up_table
(row_id INT NOT NULL,
 attribute VARCHAR(500),
 VARCHAR(700)
)
/* now manually populating this table */
INSERT INTO look_up_table
VALUES
(1, grmacolor_frame_access, black);
(2, grmacolor_frame_access, blue);
(3, grmacolor_frame_access, red);
(4, grmamaterial_frame_access, acetate);
(5, grmamaterial_frame_access, metal);
(6, grmamaterial_frame_access, nylon);
(7, grmamaterial_frame_access, plastic);

DECLARE @temp_col_val NVARCHAR (700),  @counter1 INT,
SET @counter1 = 0;
SET @column_count = (SELECT COUNT (DISTINCT attribute) FROM look_up_table);

CREATE TABLE #temp1 AS
SELECT DISTINCT attribute AS attrib,
ROW_NUMBER() OVER (ORDER BY attribute) AS seqno1,
FROM look_up_table;

WHILE (@counter1 < @column_count)
BEGIN;

SET @temp_col_val = (SELECT attrib FROM #temp1 WHERE seqno1 = @counter1;

请帮忙

【参考方案1】：

以下代码将遍历每个属性并打印出来：

declare 
    curField varchar2(100);
    resultCnt number ; 
begin    
    select count(distinct attribute) into resultCnt from look_up_table;
    for ind in 1..resultCnt loop
        select attribute into curField from (
            select attribute, rownum rwn
            from 
            (
               select distinct attribute
               from look_up_table
            )
        ) where rwn = ind;

        dbms_output.put_line (curField);
    end loop;
end;
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