資料庫建表

create table tablename (
    x1 float ,
    x2 float ,
    y float ,
    value float
   )

資料

insert into tablename (x1,x2,y,value) values (1,1.9,50,1356) , (2,2.9,50,1546) ,(3,3.9,50,1703) ,(4,4.9,50,1905) , (1,1.9,60,1768) 
-- ................. 以下比較辦理

查詢

declare @A as float 
set @A = 4.3
declare @B as float 
set @B = 70

select value from tablename where (@A between x1 and x2) and (y = @B)

(更新，之前between用法有誤，改正)

簡單的DEMO

最標準的作法：多對多

執行結果

-- 欄
CREATE TABLE col (
id INT NOT NULL AUTO_INCREMENT,
min_num FLOAT,
max_num FLOAT,
PRIMARY KEY (id)
);
INSERT INTO col
VALUES (null, 1, 1.9);
INSERT INTO col
VALUES (null, 2, 2.9);
INSERT INTO col
VALUES (null, 3, 3.9);
SELECT * FROM col;

-- 列
CREATE TABLE row (
id INT NOT NULL AUTO_INCREMENT,
value FLOAT,
PRIMARY KEY (id)
);
INSERT INTO row
VALUES (null, 50);
INSERT INTO row
VALUES (null, 60);
SELECT * FROM row;

-- 資料
CREATE TABLE data (
id INT NOT NULL AUTO_INCREMENT,
col_id INT NOT NULL,
row_id INT NOT NULL,
data VARCHAR(255),
PRIMARY KEY (id)
);
INSERT INTO data
VALUES (null, 1, 1, '1356');
INSERT INTO data
VALUES (null, 1, 2, '1768');
INSERT INTO data
VALUES (null, 1, 3, '1920');
INSERT INTO data
VALUES (null, 2, 1, '1546');
INSERT INTO data
VALUES (null, 2, 2, '1911');
INSERT INTO data
VALUES (null, 2, 3, '2034');

SELECT CONCAT(col.min_num, '~', col.max_num) as col_value, row.value as row_value, data.data
FROM col, row, data
WHERE col.id = data.col_id
AND row.id = data.row_id
-- 尋找欄=1~1.9、列=60
AND (1.3 BETWEEN col.min_num AND col.max_num)
AND row.value = 60
;