[英]select multiple rows from tow tables mysql
我正在嘗試從絲束表中選擇多個行:第一個表是施主
CREATE TABLE donor(
donor_number INT NOT NULL AUTO_INCREMENT,
d_name VARCHAR(30) NOT NULL,
mobile_number INT NOT NULL,
blood_group VARCHAR(20) NULL,
dob DATE NOT NULL,
gender ENUM('male','female') NOT NULL,
govid INT(10) NOT NULL,
PRIMARY KEY (donor_number )
);
第二張表是blood_donation
CREATE TABLE blood_donation(
donor_number INT NOT NULL,
date_of_donate DATE NOT NULL,
blood_group VARCHAR(20) NULL,
serial_number INT(10) NOT NULL,
blood_component ENUM('wb','prcb') NOT NULL,
PRIMARY KEY (donor_number , date_of_donate ),
FOREIGN KEY (donor_number) REFERENCES donor(donor_number)
);
使用以下選擇語句:
SELECT
serial_number,
blood_group
FROM blood_donation
WHERE date_of_donate = '2012-07-18'
UNION ALL
SELECT
blood_group
FROM donor
WHERE donor.donor_number=blood_donation.donor_number;
但是,我得到了錯誤
SQL state 42S22: Unknown column 'blood_donation.donor_number' in 'where clause'
any idea????
實際上,您不應該使用UNION而是JOIN :)
您查詢將如下所示
SELECT
blood_donation.serial_number,
donor.blood_group
FROM
blood_donation ,
donor
WHERE donor.donor_number = blood_donation.donor_number AND date_of_donate = '2012-07-18' ;
SELECT
dd.serial_number,
dd.blood_group
FROM blood_donation dd
inner join
donor d
on d.donor_number=dd.donor_number
WHERE dd.date_of_donate = '2012-07-18';
UNION
並不是您真正需要的,請閱讀有關JOINS的更多信息。 另外,請根據需要更改列的選擇別名。 如果您不希望在表上使用強制Inner Join
則可以使用Left Join
代替Inner Join
。
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