Jika bidang dalam tabel bersifat opsional, dimungkinkan untuk menyisipkan catatan baru atau memperbarui catatan tanpa menambahkan nilai ke bidang ini. Kemudian, bidang tersebut akan disimpan dengan nilai NULL
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Bagaimana Cara Menguji Nilai NULL? Sintaks IS NULL Sintaks BUKAN NULL Basis Data Demo Pengantar nilai MySQL INSERT INTO leads(first_name,last_name,source,email,phone)
VALUE('John','Doe','Web Search','[email protected] ',NULL);Code language: SQL (Structured Query Language) (sql)5 MySQL SELECT
*
FROM
leads
ORDER BY phone;Code language: SQL (Structured Query Language) (sql)8 dalam pernyataan SELECT
*
FROM
leads
ORDER BY phone;Code language: SQL (Structured Query Language) (sql)9 MySQL SELECT
*
FROM
leads
ORDER BY phone DESC;Code language: SQL (Structured Query Language) (sql)5 dengan INSERT INTO leads(first_name,last_name,source,email,phone)
VALUE('John','Doe','Web Search','[email protected] ',NULL);Code language: SQL (Structured Query Language) (sql)5 MySQL INSERT INTO leads(first_name,last_name,source,email,phone)
VALUE('John','Doe','Web Search','[email protected] ',NULL);Code language: SQL (Structured Query Language) (sql)5 dan indeks SELECT
*
FROM
leads
WHERE
email IS NOT NULL;Code language: SQL (Structured Query Language) (sql)4 MySQL INSERT INTO leads(first_name,last_name,source,email,phone)
VALUE('John','Doe','Web Search','[email protected] ',NULL);Code language: SQL (Structured Query Language) (sql)_5 fungsi Apa arti set kosong di MySQL? Apakah NULL atau kosong di MySQL? Apakah NULL mengatur 0 MySQL? Bagaimana cara mengatur nilai kosong ke NULL di SQL?
Catatan. Nilai NULL berbeda dengan nilai nol atau bidang yang berisi spasi. Bidang dengan nilai NULL adalah bidang yang dibiarkan kosong selama pembuatan rekaman
Bagaimana Cara Menguji Nilai NULL? It is not possible to test for NULL values with comparison operators, such as =, <, or <>.
Kami harus menggunakan operator IS NULL dan IS NOT NULL sebagai gantinya
Sintaks IS NULL
PILIH nama_kolom
Sintaks BUKAN NULL
PILIH nama_kolom
Basis Data Demo Di bawah ini adalah pilihan dari tabel "Pelanggan" di database sampel Northwind
CustomerIDCustomerNameContactNameAddressCityPostalCodeCountry1Alfreds FutterkisteMaria AndersObere Str. 57Berlin12209Jerman2Ana Trujillo Emparedados y heladosAna TrujilloAvda. de la Constitución 2222México D. F. 05021Mexico3Antonio Moreno TaqueríaAntonio MorenoMataderos 2312México D. F. 05023Meksiko4Di Sekitar TandukThomas Hardy120 Hanover Sq. LondonWA1 1DPUK5Berglunds snabbköpChristina BerglundBerguvsvägen 8LuleåS-958 22Swedia
Ringkasan. dalam tutorial ini, Anda akan belajar cara bekerja dengan nilai MySQL
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5. Selain itu, Anda akan mempelajari beberapa fungsi berguna untuk menangani nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 secara efektif
Di MySQL, nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) _5 berarti tidak diketahui. Nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 berbeda dari nol (
INSERT INTO leads(first_name,last_name,source ,phone)
VALUES
('Lily' ,'Bush' ,'Cold Calling' ,'(408)-555-1234' ),
('David' ,'William' ,'Web Search' ,'(408)-888-6789' );
Code language: SQL (Structured Query Language) ( sql ) 0) atau string kosong
INSERT INTO leads(first_name,last_name,source ,phone)
VALUES
('Lily' ,'Bush' ,'Cold Calling' ,'(408)-555-1234' ),
('David' ,'William' ,'Web Search' ,'(408)-888-6789' );
Code language: SQL (Structured Query Language) ( sql ) 1
Nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 tidak sama dengan apa pun, bahkan dirinya sendiri. Jika Anda membandingkan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dengan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 lainnya atau nilai lainnya, hasilnya adalah
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 karena nilai dari setiap nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 tidak diketahui
Umumnya, Anda menggunakan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) _5 untuk menunjukkan bahwa data tersebut hilang, tidak diketahui, atau tidak berlaku. Misalnya, nomor telepon calon pelanggan mungkin
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dan dapat ditambahkan nanti
Saat membuat tabel, Anda dapat menentukan apakah kolom menerima nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 atau tidak dengan menggunakan batasan
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 0
Misalnya, pernyataan berikut membuat tabel ________15______1
DROP TABLE IF EXISTS leads;
CREATE TABLE leads (
id INT AUTO_INCREMENT PRIMARY KEY ,
first_name VARCHAR (50 ) NOT NULL ,
last_name VARCHAR (50 ) NOT NULL ,
source VARCHAR (255 ) NOT NULL ,
email VARCHAR (100 ),
phone VARCHAR (25 )
);
Code language: SQL (Structured Query Language) ( sql ) Dalam tabel
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) _1 ini, kolom
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 3 adalah kolom primary key, oleh karena itu, tidak menerima nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5
Kolom
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 5,
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 6, dan
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 7 menggunakan batasan
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 8, oleh karena itu, Anda tidak dapat memasukkan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 ke dalam kolom ini, sedangkan kolom
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) 0 dan
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) 1 menerima nilai NULL
Anda dapat menggunakan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) _5 dalam pernyataan
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) 3 untuk menentukan bahwa data tersebut hilang. Misalnya, pernyataan berikut menyisipkan baris ke dalam tabel
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 1. Karena nomor teleponnya hilang, maka digunakan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) Karena nilai default kolom email adalah
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5, Anda dapat menghilangkan email di pernyataan
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) 3 sebagai berikut
INSERT INTO leads(first_name,last_name,source ,phone)
VALUES
('Lily' ,'Bush' ,'Cold Calling' ,'(408)-555-1234' ),
('David' ,'William' ,'Web Search' ,'(408)-888-6789' );
Code language: SQL (Structured Query Language) ( sql ) MySQL SELECT
*
FROM
leads
ORDER BY phone;Code language: SQL (Structured Query Language) (sql)8 dalam pernyataan SELECT
*
FROM
leads
ORDER BY phone;Code language: SQL (Structured Query Language) (sql)9 Untuk menetapkan nilai kolom ke
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) _5, Anda menggunakan operator penugasan (
SELECT
*
FROM
leads
ORDER BY phone DESC ;
Code language: SQL (Structured Query Language) ( sql ) 1). Misalnya, untuk memperbarui telepon dari
SELECT
*
FROM
leads
ORDER BY phone DESC ;
Code language: SQL (Structured Query Language) ( sql ) _2 ke
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5, Anda menggunakan pernyataan
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) 9 berikut
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) Jika Anda menggunakan klausa
SELECT
*
FROM
leads
ORDER BY phone DESC ;
Code language: SQL (Structured Query Language) ( sql ) 5 untuk mengurutkan hasil yang ditetapkan dalam urutan menaik, MySQL menganggap nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 lebih rendah dari nilai lain, oleh karena itu, MySQL menyajikan nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 terlebih dahulu
Pernyataan berikut mengurutkan prospek berdasarkan nomor telepon dalam urutan menaik
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) _
Jika Anda menggunakan
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) 0, nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 muncul di akhir rangkaian hasil. Lihat contoh berikut.
SELECT
*
FROM
leads
ORDER BY phone DESC ;
Code language: SQL (Structured Query Language) ( sql ) Untuk menguji
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dalam kueri, gunakan operator
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) 3 atau
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) 4 dalam klausa
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) 5.
Misalnya, untuk mendapatkan prospek yang belum memberikan nomor telepon, Anda menggunakan operator
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) 6 sebagai berikut
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) Anda dapat menggunakan operator
SELECT
*
FROM
leads
WHERE
phone IS NULL ;
Code language: SQL (Structured Query Language) ( sql ) 7 untuk mendapatkan semua prospek yang memberikan alamat email.
SELECT
*
FROM
leads
WHERE
email IS NOT NULL ;
Code language: SQL (Structured Query Language) ( sql ) Meskipun
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 tidak sama dengan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5, dua nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 sama dalam klausa
SELECT
*
FROM
leads
WHERE
email IS NOT NULL ;
Code language: SQL (Structured Query Language) ( sql ) 1.
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) Kueri mengembalikan hanya dua baris karena baris yang kolom emailnya adalah
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dikelompokkan menjadi satu.
Saat Anda menggunakan batasan UNIK atau indeks UNIK pada kolom, Anda dapat memasukkan beberapa nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 ke dalam kolom tersebut. Tidak apa-apa karena dalam kasus ini, MySQL menganggap nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 berbeda
Mari verifikasi poin ini dengan membuat indeks
SELECT
*
FROM
leads
WHERE
email IS NOT NULL ;
Code language: SQL (Structured Query Language) ( sql ) 4 untuk kolom
SELECT
*
FROM
leads
ORDER BY phone;
Code language: SQL (Structured Query Language) ( sql ) 1
CREATE UNIQUE INDEX idx_phone ON leads(phone);
Code language: SQL (Structured Query Language) ( sql ) Perhatikan bahwa jika Anda menggunakan mesin penyimpanan BDB, MySQL menganggap nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 sama sehingga Anda tidak dapat memasukkan beberapa nilai
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 ke dalam kolom yang memiliki batasan unik
MySQL menyediakan beberapa fungsi berguna yang menangani NULL secara efektif.
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 2,
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 3, dan
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 4
Fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) _2 menerima dua parameter. Fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) _2 mengembalikan argumen pertama jika bukan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5, jika tidak, mengembalikan argumen kedua
Misalnya, pernyataan berikut mengembalikan nomor telepon jika bukan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 sebaliknya, pernyataan ini mengembalikan
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 9 bukan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 0
Fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 3 menerima daftar argumen dan mengembalikan argumen non-NULL pertama. Misalnya, Anda dapat menggunakan fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) _3 untuk menampilkan informasi kontak prospek berdasarkan prioritas informasi dalam urutan berikut. telepon, email, dan N/A.
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 1
Fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 4 menerima dua argumen. Jika kedua argumen sama, fungsi ________65______4 mengembalikan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5. Jika tidak, ia mengembalikan argumen pertama.
Fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) _4 berguna ketika Anda memiliki
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dan nilai string kosong dalam kolom. Misalnya, secara tidak sengaja, Anda menyisipkan baris berikut ke dalam tabel
UPDATE leads
SET
phone = NULL
WHERE
id = 3 ;
Code language: SQL (Structured Query Language) ( sql ) 1
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) _2
Telepon adalah string kosong, bukan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5
Jika Anda ingin mendapatkan informasi kontak prospek, Anda berakhir dengan telepon kosong alih-alih email sebagai permintaan berikut
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 1
Untuk memperbaikinya, Anda menggunakan fungsi
SELECT
id , first_name, last_name, email, phone
FROM
leads
GROUP BY email;
Code language: SQL (Structured Query Language) ( sql ) 4 untuk membandingkan telepon dengan string kosong, jika sama, ia mengembalikan
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5, jika tidak, ia mengembalikan nomor telepon.
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 4
Dalam tutorial ini, Anda telah mempelajari cara bekerja dengan MySQL
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dan cara menggunakan beberapa fungsi praktis untuk menangani
INSERT INTO leads(first_name,last_name,source ,email,phone)
VALUE ('John' ,'Doe' ,'Web Search' ,'[email protected] ' ,NULL );
Code language: SQL (Structured Query Language) ( sql ) 5 dalam kueri.
Apa arti set kosong di MySQL?
Jika ada 'set kosong' di set hasil kueri MySQL maka itu berarti bahwa MySQL tidak mengembalikan baris dan juga tidak ada kesalahan dalam kueri .
Apakah NULL atau kosong di MySQL?
Konsep NULL dan string kosong sering menimbulkan kebingungan karena banyak orang menganggap NULL sama dengan string kosong MySQL. Namun, bukan itu masalahnya. Sebuah string kosong adalah contoh string dengan panjang nol. Namun, NULL tidak memiliki nilai sama sekali .
Apakah NULL mengatur 0 MySQL?
Gunakan fungsi IFNULL atau COALESCE() untuk mengonversi MySQL NULL ke 0 . Sisipkan beberapa record dalam tabel menggunakan perintah insert. Tampilkan semua rekaman dari tabel menggunakan pernyataan pilih.
Bagaimana cara mengatur nilai kosong ke NULL di SQL?
Anda perlu menggunakan fungsi NULLIF() dari MySQL . Sintaksnya adalah sebagai berikut. SELECT NULLIF(yourCoumnName,' ') sebagai anyVariableName dari yourTableName; .
