Karibu kwenye Somo la 17 la MySQL Database Full Course kwa Kiswahili.

Katika somo lililopita tulijifunza kutumia:

LIKE

pamoja na wildcards:

%
_

kutafuta data kwa kutumia sehemu ya jina, neno, email, phone number au text nyingine.

Sasa tutajifunza operators tatu muhimu sana:

IN

NOT IN

na:

BETWEEN

Operators hizi hutusaidia kuandika queries fupi, safi na rahisi kusoma pale tunapokuwa na conditions nyingi.

Kwa mfano, badala ya kuandika:

SELECT *
FROM students
WHERE student_id = 1
OR student_id = 3
OR student_id = 5;

tunaweza kuandika:

SELECT *
FROM students
WHERE student_id IN (1, 3, 5);

Hii ni rahisi zaidi.

Malengo ya Somo

Baada ya kumaliza somo hili utaweza:

• Kuelewa IN
• Kuelewa NOT IN
• Kuelewa BETWEEN
• Kuchagua IDs nyingi
• Kuchagua categories nyingi
• Kuchagua classes nyingi
• Kuchagua subjects nyingi
• Kutafuta marks ndani ya range
• Kutafuta prices ndani ya range
• Kutafuta ages ndani ya range
• Kutumia NOT BETWEEN
• Kuchanganya operators hizi na ORDER BY
• Kutumia katika mifumo halisi

1. IN ni Nini?

IN hutumika kuangalia kama value ipo katika list ya values tulizotaja.

Mfano:

SELECT *
FROM students
WHERE student_id IN (1, 3, 5);

Hii ina maana:

Onyesha students wenye ID 1, 3 au 5.

2. Syntax ya IN

Muundo wake ni:

SELECT *
FROM table_name
WHERE column_name IN (value1, value2, value3);

Mfano:

SELECT *
FROM students
WHERE class_name IN ('Form One', 'Form Two');

3. Tutumie Table ya Students

CREATE TABLE students (
    student_id INT PRIMARY KEY AUTO_INCREMENT,
    student_name VARCHAR(100),
    gender VARCHAR(10),
    age INT,
    class_name VARCHAR(50)
);

Ingiza data:

INSERT INTO students (
    student_name,
    gender,
    age,
    class_name
)
VALUES
('Asha Mussa', 'Female', 16, 'Form One'),
('John Peter', 'Male', 17, 'Form Two'),
('Neema Joseph', 'Female', 15, 'Form One'),
('Peter Michael', 'Male', 18, 'Form Three'),
('Anna Charles', 'Female', 17, 'Form Two'),
('Joseph Mussa', 'Male', 19, 'Form Four'),
('Rehema John', 'Female', 18, 'Form Three');

4. Kuchagua Students kwa IDs Nyingi

SELECT *
FROM students
WHERE student_id IN (1, 3, 5);

Hii inaweza kuonyesha:

1   Asha Mussa
3   Neema Joseph
5   Anna Charles

5. IN Badala ya OR

Query hii:

SELECT *
FROM students
WHERE student_id = 1
OR student_id = 3
OR student_id = 5;

inaweza kubadilishwa kuwa:

SELECT *
FROM students
WHERE student_id IN (1, 3, 5);

Queries zote zinaweza kutoa result sawa.

Lakini IN ni rahisi kusoma.

6. IN na Text Values

Kwa text tunatumia quotes.

Mfano:

SELECT *
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two'
);

Hii itaonyesha students wa Form One na Form Two.

7. Kuchagua Gender kwa IN

SELECT *
FROM students
WHERE gender IN ('Male', 'Female');

Ikiwa table ina Male na Female tu, hii inaweza kuonyesha records zote.

Lakini concept hii ni muhimu kama column ina values nyingi zaidi.

8. IN kwenye Subjects

Fikiria table:

CREATE TABLE marks (
    mark_id INT PRIMARY KEY AUTO_INCREMENT,
    student_name VARCHAR(100),
    subject VARCHAR(100),
    score DECIMAL(5,2)
);

Data:

INSERT INTO marks (
    student_name,
    subject,
    score
)
VALUES
('Asha Mussa', 'Mathematics', 85),
('John Peter', 'Physics', 72),
('Neema Joseph', 'English', 91),
('Peter Michael', 'Biology', 64),
('Anna Charles', 'Mathematics', 78),
('Joseph Mussa', 'Chemistry', 55);

9. Mathematics au Physics

SELECT *
FROM marks
WHERE subject IN ('Mathematics', 'Physics');

Hii ni sawa na:

SELECT *
FROM marks
WHERE subject = 'Mathematics'
OR subject = 'Physics';

10. Subjects Tatu

SELECT *
FROM marks
WHERE subject IN (
    'Mathematics',
    'Physics',
    'Chemistry'
);

11. NOT IN ni Nini?

NOT IN hufanya kinyume cha IN.

Mfano:

SELECT *
FROM students
WHERE class_name NOT IN ('Form One', 'Form Two');

Hii ina maana:

Onyesha students ambao hawapo Form One wala Form Two.

12. NOT IN kwa IDs

SELECT *
FROM students
WHERE student_id NOT IN (1, 2, 3);

Hii itaonyesha records isipokuwa IDs 1, 2 na 3.

13. NOT IN kwa Subjects

SELECT *
FROM marks
WHERE subject NOT IN (
    'Mathematics',
    'Physics'
);

Hii inaweza kuonyesha:

English
Biology
Chemistry

14. IN na ORDER BY

SELECT *
FROM students
WHERE class_name IN ('Form One', 'Form Two')
ORDER BY student_name ASC;

Students watachaguliwa kwanza, kisha majina yatapangwa A–Z.

15. IN na LIMIT

SELECT *
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two'
)
ORDER BY student_id ASC
LIMIT 5;

16. BETWEEN ni Nini?

BETWEEN hutumika kuchagua values zilizo ndani ya range fulani.

Mfano:

SELECT *
FROM students
WHERE age BETWEEN 16 AND 18;

Hii ina maana:

Chagua students wenye age kuanzia 16 mpaka 18.

17. Syntax ya BETWEEN

SELECT *
FROM table_name
WHERE column_name BETWEEN value1 AND value2;

Mfano:

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 80;

18. BETWEEN Inajumuisha Boundary Values

Hili ni muhimu.

Query:

WHERE score BETWEEN 50 AND 80

kwa kawaida inajumuisha:

50
na
80

Kwa hiyo ni sawa na concept:

WHERE score >= 50
AND score <= 80;

19. Age Kati ya 16 na 18

SELECT *
FROM students
WHERE age BETWEEN 16 AND 18;

Inaweza kuonyesha students wenye:

16
17
18

20. Marks Kati ya 50 na 80

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 80;

Inaweza kuonyesha:

55
64
72
78
80

ikiwa values hizo zipo.

21. Marks Kati ya 80 na 100

SELECT *
FROM marks
WHERE score BETWEEN 80 AND 100;

Hii inaweza kutumika kupata high scores.

22. BETWEEN na ORDER BY

SELECT
    student_name,
    score
FROM marks
WHERE score BETWEEN 50 AND 80
ORDER BY score DESC;

Hii itachagua marks 50–80 na kuzipanga kubwa hadi ndogo.

23. NOT BETWEEN

NOT BETWEEN huchagua values zilizo nje ya range.

Mfano:

SELECT *
FROM marks
WHERE score NOT BETWEEN 50 AND 80;

Hii inaweza kurudisha:

• Scores chini ya 50
• Scores juu ya 80

24. Students Nje ya Age Range

SELECT *
FROM students
WHERE age NOT BETWEEN 16 AND 18;

Inaweza kuonyesha students wenye age:

15
19
20

na nyingine zilizo nje ya range.

25. Products Table

Tutengeneze:

CREATE TABLE products (
    product_id INT PRIMARY KEY AUTO_INCREMENT,
    product_name VARCHAR(100),
    category VARCHAR(100),
    price DECIMAL(10,2),
    quantity INT
);

Data:

INSERT INTO products (
    product_name,
    category,
    price,
    quantity
)
VALUES
('Laptop', 'Electronics', 1500000, 5),
('Mouse', 'Accessories', 25000, 50),
('Keyboard', 'Accessories', 45000, 30),
('Printer', 'Electronics', 450000, 8),
('Office Chair', 'Furniture', 180000, 10),
('Desk', 'Furniture', 250000, 6);

26. Products za Categories Nyingi

SELECT *
FROM products
WHERE category IN (
    'Electronics',
    'Furniture'
);

27. Products Ambazo Si Accessories

SELECT *
FROM products
WHERE category NOT IN ('Accessories');

Unaweza pia kuandika:

SELECT *
FROM products
WHERE category != 'Accessories';

Kwa value moja, zote zinaweza kutumika.

28. Product Prices Kati ya 100000 na 500000

SELECT *
FROM products
WHERE price BETWEEN 100000 AND 500000;

Inaweza kuonyesha:

Printer
Office Chair
Desk

kulingana na prices zilizopo.

29. Products Nje ya Price Range

SELECT *
FROM products
WHERE price NOT BETWEEN 100000 AND 500000;

30. Quantity Kati ya 5 na 10

SELECT *
FROM products
WHERE quantity BETWEEN 5 AND 10;

Hii inaweza kusaidia kwenye stock analysis.

31. IN na AND

Tunaweza kuchanganya:

SELECT *
FROM students
WHERE class_name IN ('Form One', 'Form Two')
AND gender = 'Female';

Hii itaonyesha Female students wa Form One au Form Two.

32. IN na BETWEEN

Mfano:

SELECT *
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two',
    'Form Three'
)
AND age BETWEEN 16 AND 18;

Hii ni query yenye nguvu zaidi.

33. Subjects Maalumu na Marks Range

SELECT *
FROM marks
WHERE subject IN (
    'Mathematics',
    'Physics'
)
AND score BETWEEN 50 AND 80;

Hii ina maana:

• Subject iwe Mathematics au Physics
• Score iwe kati ya 50 na 80

34. IN na OR

Unaweza pia kukutana na:

SELECT *
FROM students
WHERE class_name IN ('Form One', 'Form Two')
OR age = 19;

Hii itaonyesha:

• Form One
• Form Two
• Au student mwenye age 19

35. Parentheses na Conditions

Mfano:

SELECT *
FROM students
WHERE (
    class_name IN ('Form One', 'Form Two')
    OR age = 19
)
AND gender = 'Male';

Parentheses hufanya logic iwe wazi.

36. BETWEEN na Dates

BETWEEN inaweza pia kutumika kwenye dates.

Fikiria table:

CREATE TABLE payments (
    payment_id INT PRIMARY KEY AUTO_INCREMENT,
    student_name VARCHAR(100),
    amount DECIMAL(10,2),
    paid_date DATE
);

Tunaweza kufanya:

SELECT *
FROM payments
WHERE paid_date BETWEEN '2026-01-01' AND '2026-12-31';

Hii inaweza kuonyesha payments zilizopo ndani ya mwaka 2026.

37. BETWEEN na DATETIME

Ukiwa na DATETIME, unatakiwa kuwa makini zaidi na time component.

Mfano:

WHERE created_at BETWEEN
'2026-01-01 00:00:00'
AND
'2026-01-31 23:59:59'

Kwa systems kubwa, date-range logic inaweza kuandikwa kwa njia nyingine salama zaidi kulingana na requirement.

38. IN Katika Mfumo wa Shule

Academic master anaweza kutaka students kutoka classes tatu:

SELECT *
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two',
    'Form Three'
);

Badala ya kuandika OR mara nyingi.

39. IN Katika Mfumo wa Marks

Tafuta marks za science subjects:

SELECT *
FROM marks
WHERE subject IN (
    'Physics',
    'Chemistry',
    'Biology'
);

40. NOT IN Katika Mfumo wa Marks

Tafuta marks ambazo si science subjects:

SELECT *
FROM marks
WHERE subject NOT IN (
    'Physics',
    'Chemistry',
    'Biology'
);

41. BETWEEN Katika Mfumo wa Results

Tafuta students wenye marks 50 hadi 64:

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 64;

Inaweza kusaidia wakati wa kuunda grade ranges.

Baadaye tutajifunza zaidi kuhusu conditions na grading logic.

42. Marks 65 hadi 74

SELECT *
FROM marks
WHERE score BETWEEN 65 AND 74;

43. Marks 75 hadi 100

SELECT *
FROM marks
WHERE score BETWEEN 75 AND 100;

44. BETWEEN Katika Accounting System

Fikiria contributions:

CREATE TABLE contributions (
    contribution_id INT PRIMARY KEY AUTO_INCREMENT,
    student_name VARCHAR(100),
    amount DECIMAL(10,2),
    paid_date DATE
);

Tafuta contributions kati ya 10000 na 50000:

SELECT *
FROM contributions
WHERE amount BETWEEN 10000 AND 50000;

45. Payments za Date Range

SELECT *
FROM contributions
WHERE paid_date BETWEEN
'2026-01-01'
AND
'2026-06-30';

Hii inaweza kutumika katika reports.

46. IN Katika Blog System

Tafuta posts za categories maalumu:

SELECT *
FROM posts
WHERE category IN (
    'MySQL',
    'PHP',
    'JavaScript'
);

47. NOT IN Katika Blog System

SELECT *
FROM posts
WHERE category NOT IN (
    'Politics',
    'Sports'
);

48. IN Katika User Management

Tafuta users wenye roles fulani:

SELECT *
FROM users
WHERE role IN (
    'admin',
    'teacher'
);

49. NOT IN katika User Management

SELECT *
FROM users
WHERE role NOT IN (
    'admin',
    'super_admin'
);

Hii inaweza kutumika kwenye filters, lakini authorization halisi haipaswi kutegemea query moja pekee.

50. Makosa ya Kawaida – Kusahau Parentheses za IN

Mfano mbaya:

SELECT *
FROM students
WHERE student_id IN 1, 2, 3;

Sahihi:

SELECT *
FROM students
WHERE student_id IN (1, 2, 3);

51. Makosa ya Kawaida – Text Bila Quotes

Mfano mbaya:

SELECT *
FROM students
WHERE class_name IN (Form One, Form Two);

Sahihi:

SELECT *
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two'
);

52. Makosa ya Kawaida – BETWEEN Bila AND

Mfano mbaya:

SELECT *
FROM marks
WHERE score BETWEEN 50, 80;

Sahihi:

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 80;

53. Makosa ya Kawaida – Range Kinyume

Mfano:

SELECT *
FROM marks
WHERE score BETWEEN 80 AND 50;

Hii si range tuliyokusudia.

Kwa kawaida lower value iwe kwanza:

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 80;

54. Makosa ya Kawaida – Kudhani BETWEEN Haijumuishi Boundaries

Kumbuka:

BETWEEN 50 AND 80

kwa kawaida inajumuisha:

50
80

Kwa hiyo ni sawa na:

score >= 50
AND score <= 80

55. Makosa ya Kawaida – NOT IN na NULL

Hili ni jambo la muhimu zaidi unapofika advanced queries.

Ikiwa list au subquery yenye NOT IN inahusisha NULL, matokeo yanaweza kuwa tofauti na unavyotarajia kutokana na SQL three-valued logic.

Kwa beginner, ukitumia list ya kawaida kama:

NOT IN (1, 2, 3)

hakuna tatizo.

Masuala ya NULL tutajifunza vizuri zaidi katika somo la NULL.

56. IN vs OR

Mfano wa OR:

SELECT *
FROM students
WHERE student_id = 1
OR student_id = 2
OR student_id = 3
OR student_id = 4;

Mfano wa IN:

SELECT *
FROM students
WHERE student_id IN (1, 2, 3, 4);

IN ni:

• Fupi
• Rahisi kusoma
• Rahisi kuongeza values

57. BETWEEN vs AND

Mfano:

SELECT *
FROM marks
WHERE score >= 50
AND score <= 80;

Unaweza kuandika:

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 80;

Zote zinaweza kutoa result sawa kwa range hii.

58. NOT BETWEEN vs Comparison Operators

Hii:

SELECT *
FROM marks
WHERE score NOT BETWEEN 50 AND 80;

inafanana na concept:

SELECT *
FROM marks
WHERE score < 50
OR score > 80;

59. IN na UPDATE

IN inaweza pia kutumika na UPDATE.

Mfano:

UPDATE students
SET class_name = 'Special Class'
WHERE student_id IN (1, 3, 5);

Hii inaweza kubadilisha records tatu.

Kabla ya kufanya hivyo, ni vizuri kuangalia:

SELECT *
FROM students
WHERE student_id IN (1, 3, 5);

60. IN na DELETE

Unaweza kufanya:

DELETE FROM students
WHERE student_id IN (2, 4, 6);

Lakini hii inaweza kufuta records nyingi.

Kwanza:

SELECT *
FROM students
WHERE student_id IN (2, 4, 6);

Hakikisha records ni sahihi kabla ya DELETE.

61. BETWEEN na UPDATE

Mfano:

UPDATE products
SET discount = 5
WHERE price BETWEEN 100000 AND 500000;

ikiwa discount column ipo.

Records zote katika price range zinaweza kubadilishwa.

62. BETWEEN na DELETE

Mfano:

DELETE FROM logs
WHERE log_id BETWEEN 1 AND 100;

Hii inaweza kufuta records nyingi sana.

Hivyo kabla yake:

SELECT *
FROM logs
WHERE log_id BETWEEN 1 AND 100;

63. Query Order

Mfano:

SELECT
    student_name,
    class_name,
    age
FROM students
WHERE class_name IN ('Form One', 'Form Two')
AND age BETWEEN 15 AND 18
ORDER BY student_name ASC
LIMIT 10;

Mpangilio wetu ni:

SELECT
FROM
WHERE
ORDER BY
LIMIT

64. Mfano wa Query Kamili ya School System

SELECT
    student_id,
    student_name,
    gender,
    age,
    class_name
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two'
)
AND age BETWEEN 15 AND 18
ORDER BY class_name ASC, student_name ASC
LIMIT 20;

Query hii:

1. Inachagua columns.
2. Inachagua Form One na Form Two.
3. Inachagua age 15–18.
4. Inapanga kwa class na jina.
5. Inaonyesha records 20 tu.

65. Mfano wa Marks Report

SELECT
    student_name,
    subject,
    score
FROM marks
WHERE subject IN (
    'Mathematics',
    'Physics',
    'Chemistry'
)
AND score BETWEEN 50 AND 100
ORDER BY score DESC;

Hii inaweza kutengeneza report ya science subjects kwa waliofanya vizuri.

66. Mfano wa Product Filter

SELECT
    product_name,
    category,
    price
FROM products
WHERE category IN (
    'Electronics',
    'Furniture'
)
AND price BETWEEN 100000 AND 1000000
ORDER BY price ASC;

67. Mfano wa Search Filters

Website inaweza kuwa na filters:

Category:
Electronics
Furniture

Minimum Price:
100000

Maximum Price:
500000

SQL concept:

SELECT *
FROM products
WHERE category IN (
    'Electronics',
    'Furniture'
)
AND price BETWEEN 100000 AND 500000;

68. IN na Prepared Statements

Katika PHP halisi, values kutoka kwa user hazipaswi kuingizwa moja kwa moja bila validation.

Kwa queries zenye dynamic IN, placeholders zinapaswa kutengenezwa kulingana na idadi ya values na kutumika pamoja na prepared statements.

Tutajifunza hili baadaye kwenye PHP + MySQL.

69. Je IN Inaweza Kuwa na Value Moja?

Ndiyo.

SELECT *
FROM students
WHERE student_id IN (1);

Inaweza kufanya kazi.

Lakini ikiwa una value moja tu, hii ni rahisi zaidi:

SELECT *
FROM students
WHERE student_id = 1;

70. Je IN Inaweza Kuwa na Values Nyingi?

Ndiyo.

Mfano:

SELECT *
FROM students
WHERE student_id IN (
    1, 2, 3, 4, 5, 6, 7, 8
);

71. IN na Subquery

Baadaye tutajifunza advanced usage kama:

SELECT *
FROM students
WHERE student_id IN (
    SELECT student_id
    FROM marks
);

Hii inaitwa matumizi ya IN pamoja na subquery.

Tutafika kwenye Subqueries katika masomo ya advanced.

72. Mazoezi ya Somo

Tumia table ya students.

Andika queries za:

1. Kuonyesha students wenye IDs 1, 3 na 5.
2. Kuonyesha Form One na Form Two.
3. Kuonyesha students ambao si Form One wala Form Two.
4. Kuonyesha age 16 mpaka 18.
5. Kuonyesha students ambao age yao si 16–18.
6. Kuonyesha Female students wa Form One au Form Two.
7. Kuonyesha Form One/Form Two wenye age 15–17 na kupanga kwa jina.

73. Mazoezi ya Marks

Tumia table ya marks.

Andika queries za:

1. Mathematics na Physics.
2. Mathematics, Physics na Chemistry.
3. Subjects ambazo si Mathematics wala Physics.
4. Scores 50–80.
5. Scores 80–100.
6. Scores ambazo si 50–80.
7. Mathematics au Physics zenye score 50–80.
8. Panga result hiyo kwa score DESC.

74. Challenge ya Products

Tumia table:

products

yenye:

product_id
product_name
category
price
quantity

Fanya yafuatayo:

1. Chagua Electronics na Furniture.
2. Chagua products ambazo si Accessories.
3. Chagua price 100000–500000.
4. Chagua quantity 5–20.
5. Chagua Electronics/Furniture zenye price 100000–500000.
6. Panga kwa price DESC.
7. Onyesha records 5 tu.

Mfano:

SELECT *
FROM products
WHERE category IN (
    'Electronics',
    'Furniture'
)
AND price BETWEEN 100000 AND 500000
ORDER BY price DESC
LIMIT 5;

75. Challenge ya Mfumo wa Shule

Tengeneza query inayotafuta:

• Female students
• Wa Form One, Form Two au Form Three
• Wenye age kati ya 15 na 18
• Wapangwe kwa class
• Ndani ya class wapangwe kwa jina A–Z

Jibu linaweza kuwa:

SELECT *
FROM students
WHERE gender = 'Female'
AND class_name IN (
    'Form One',
    'Form Two',
    'Form Three'
)
AND age BETWEEN 15 AND 18
ORDER BY class_name ASC, student_name ASC;

76. Maswali ya Kujipima

Jaribu kujibu:

1. IN inatumika kufanya nini?
2. NOT IN inafanya nini?
3. BETWEEN inafanya nini?
4. NOT BETWEEN inafanya nini?
5. Je BETWEEN 50 AND 80 inajumuisha 50 na 80?
6. Kuna tofauti gani kati ya IN na OR nyingi?
7. Kuna tofauti gani kati ya BETWEEN na >= pamoja na <=?
8. Unawezaje kuchagua IDs 1, 5 na 8?
9. Unawezaje kuchagua Mathematics, Physics na Biology?
10. Unawezaje kupata price kati ya 50000 na 200000?
11. Unawezaje kupata values zilizo nje ya range hiyo?
12. Je IN inaweza kutumika kwenye UPDATE na DELETE?

77. Muhtasari wa Somo

Katika somo hili tumejifunza operators tatu muhimu:

IN

NOT IN

na:

BETWEEN

IN hutumika kuchagua values nyingi:

SELECT *
FROM students
WHERE student_id IN (1, 3, 5);

NOT IN hutenga values fulani:

SELECT *
FROM students
WHERE class_name NOT IN (
    'Form One',
    'Form Two'
);

BETWEEN hutafuta range:

SELECT *
FROM marks
WHERE score BETWEEN 50 AND 80;

NOT BETWEEN hutafuta values zilizo nje ya range:

SELECT *
FROM marks
WHERE score NOT BETWEEN 50 AND 80;

Tumeona pia query yenye conditions nyingi:

SELECT *
FROM students
WHERE class_name IN (
    'Form One',
    'Form Two'
)
AND age BETWEEN 15 AND 18
ORDER BY student_name ASC;

Sasa tunaweza kutengeneza filters zenye nguvu zaidi kwa kutumia SQL.

Somo Linalofuata

Katika Somo la 18 tutajifunza:

NULL, IS NULL, IS NOT NULL na DEFAULT Values Katika MySQL

Tutajifunza:

• NULL ni nini
• Tofauti ya NULL na empty string
• Tofauti ya NULL na 0
• IS NULL
• IS NOT NULL
• Kwa nini = NULL si sahihi kwa kawaida
• DEFAULT
• Kutengeneza column yenye default value
• Kuweka NULL kwa INSERT
• Kuweka NULL kwa UPDATE
• Kutafuta records zisizo na phone number
• Default status
• Default dates
• Makosa ya kawaida
• Mazoezi na challenges

Hili litatusaidia kuelewa vizuri jinsi MySQL inavyoshughulikia data ambayo haijapatikana au haijaingizwa.