Skip to content

Commit ebd5baf

Browse files
sanjay-kvsanjay-kv
committed
added sql table alter
1 parent 3556dca commit ebd5baf

File tree

6 files changed

+505
-512
lines changed

6 files changed

+505
-512
lines changed

‎docs/sql/SQL-basics/filtering-data.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -86,7 +86,7 @@ For example, consider a table named `Friends`. Below is how a simple table might
8686
8787
```sql title="Creating SQL Tables. "
8888
SELECT *
89-
FROM membership
89+
FROM friends
9090
WHERE type = 'pro';
9191
```
9292

‎docs/sql/table-transformation/alter-table.md

Lines changed: 235 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,235 @@
1+
---
2+
id: alter-table
3+
title: Alter Table Data
4+
sidebar_label: Alter Table Data
5+
sidebar_position: 3
6+
tags: [html, web-development, attributes, values]
7+
description: In this tutorial, you will learn about HTML attributes and values. HTML attributes provide additional information about elements, and values define the specific settings or properties of the attributes.
8+
keywords: [html, web development, attributes, values, html attributes, html values, html tutorial, html basics, web design, web pages, websites, html structure, html attributes tutorial, html values tutorial, html in 2024]
9+
---
10+
11+
12+
# 📗 Alter Table Data
13+
14+
Let’s say you’re a small business owner, and your business is growing! You realize you need to keep track of discounts for each order. To do this, you need to change the structure of your existing table by adding a new column.
15+
16+
Suppose you have an `orders` table like this:
17+
18+
To track discounts, you want to add a `discount` column. In SQL, you can modify the table structure using the `ALTER TABLE` statement:
19+
20+
21+
:::info
22+
<Tabs>
23+
<TabItem value="SQL Table" label="SQL Table">
24+
```sql title="Orders Table"
25+
| order_no | order_status | place_of_order |
26+
|----------|--------------|----------------|
27+
| 101 | Delivered | Amazon |
28+
| 512 | Delivered | Amazon |
29+
| 432 | Shipped | Pedbubble |
30+
| 984 | Processing | Store |
31+
| 566 | Delivered | Store |
32+
```
33+
</TabItem>
34+
35+
<TabItem value="SQL Code" label="SQL Code">
36+
37+
38+
```sql
39+
ALTER TABLE orders
40+
ADD discount;
41+
```
42+
43+
</TabItem>
44+
45+
<TabItem value="how-git-works" label="Output ">
46+
47+
| order_no | order_status | place_of_order | discount |
48+
|----------|--------------|----------------|----------|
49+
| 101 | Delivered | Amazon | |
50+
| 512 | Delivered | Amazon | |
51+
| 432 | Shipped | Pedbubble | |
52+
| 984 | Processing | Store | |
53+
| 566 | Delivered | Store | |
54+
</TabItem>
55+
</Tabs>
56+
57+
58+
59+
---
60+
61+
✅ This is your first step in understanding how data is structured in relational databases. Once you master rows, you're on your way to writing powerful SQL queries!.
62+
63+
> We can add new col with `ADD` Keywords
64+
65+
:::
66+
67+
## 🗑️ Deleting a Column from a Table
68+
69+
Sometimes, you may need to remove a column from an existing table. You can do this using the `DROP COLUMN` command with `ALTER TABLE`. For example, to remove the `place_of_order` column from the `orders` table:
70+
71+
<Tabs>
72+
<TabItem value="SQL Table" label="SQL Table">
73+
74+
```sql title="Orders Table"
75+
| order_no | order_status | order_amt | customer_id | place_of_order |
76+
|----------|--------------|-----------|-------------|----------------|
77+
| 101 | Delivered | 550 | 3001 | Amazon |
78+
| 512 | Delivered | 113 | 3001 | Amazon |
79+
| 984 | Processing | 54 | 3012 | Store |
80+
| 566 | Delivered | 850 | 3120 | Store |
81+
| 432 | Shipped | 99 | 3003 | Amazon |
82+
```
83+
</TabItem>
84+
85+
<TabItem value="SQL Code" label="SQL Code">
86+
87+
```sql
88+
ALTER TABLE orders
89+
DROP COLUMN place_of_order;
90+
SELECT * FROM orders;
91+
```
92+
93+
</TabItem>
94+
95+
<TabItem value="Output" label="Output">
96+
97+
| order_no | order_status | order_amt | customer_id |
98+
|----------|--------------|-----------|-------------|
99+
| 101 | Delivered | 550 | 3001 |
100+
| 512 | Delivered | 113 | 3001 |
101+
| 984 | Processing | 54 | 3012 |
102+
| 566 | Delivered | 850 | 3120 |
103+
| 432 | Shipped | 99 | 3003 |
104+
105+
</TabItem>
106+
</Tabs>
107+
108+
:::tip
109+
✅ Tip: Always double-check before dropping a column, as this operation is irreversible and will permanently remove the data in that column.
110+
:::
111+
112+
## ✏️ Renaming a Column in a Table
113+
114+
You can rename a column in SQL using the `RENAME COLUMN` command with `ALTER TABLE`. Specify the original column name after `RENAME COLUMN`, and the new name after `TO`. For example, to rename the `order_amt` column to `amount` in the `orders` table:
115+
116+
<Tabs>
117+
<TabItem value="SQL Table" label="SQL Table">
118+
119+
```sql title="Orders Table"
120+
| order_no | order_status | order_amt | customer_id | discount |
121+
|----------|--------------|-----------|-------------|----------|
122+
| 101 | Delivered | 550 | 3001 | |
123+
| 512 | Delivered | 113 | 3001 | |
124+
| 984 | Processing | 54 | 3012 | |
125+
| 566 | Delivered | 850 | 3120 | |
126+
| 432 | Shipped | 99 | 3003 | |
127+
```
128+
</TabItem>
129+
130+
<TabItem value="SQL Code" label="SQL Code">
131+
132+
```sql
133+
ALTER TABLE orders
134+
RENAME COLUMN order_amt TO amount;
135+
SELECT * FROM orders;
136+
```
137+
138+
</TabItem>
139+
140+
<TabItem value="Output" label="Output">
141+
142+
| order_no | order_status | amount | customer_id | discount |
143+
|----------|--------------|--------|-------------|----------|
144+
| 101 | Delivered | 550 | 3001 | |
145+
| 512 | Delivered | 113 | 3001 | |
146+
| 984 | Processing | 54 | 3012 | |
147+
| 566 | Delivered | 850 | 3120 | |
148+
| 432 | Shipped | 99 | 3003 | |
149+
150+
</TabItem>
151+
</Tabs>
152+
153+
:::tip
154+
✅ Tip: Use `ALTER TABLE ... RENAME COLUMN ... TO ...` to safely rename columns without losing data.
155+
:::
156+
157+
158+
159+
## ✅ What You Have Learned
160+
161+
In this module, you explored essential SQL table transformation skills, including:
162+
163+
- **Altering Table Structure**
164+
How to use the `ALTER TABLE` statement to add, remove, or rename columns in an existing table.
165+
166+
- **Adding Columns**
167+
Using `ADD` with `ALTER TABLE` to introduce new columns, such as tracking discounts for orders.
168+
169+
- **Deleting Columns**
170+
Removing unnecessary columns with `DROP COLUMN` to keep your table structure relevant.
171+
172+
- **Renaming Columns**
173+
Renaming columns safely using `RENAME COLUMN` to improve clarity or adapt to changing requirements.
174+
175+
- **Best Practices**
176+
Double-checking before dropping columns (as this is irreversible), and using clear, descriptive column names for maintainability.
177+
178+
These skills help you adapt your database schema as your application or business needs evolve.
179+
180+
---
181+
182+
## 📝 Quiz: Test Your Knowledge
183+
#### 1. How can you remove the `place_of_order` column from the `orders` table in SQL?
184+
185+
Here is the original `orders` table:
186+
187+
188+
| order_no | order_status | order_amt | customer_id | place_of_order |
189+
|----------|--------------|-----------|-------------|----------------|
190+
| 101 | Delivered | 550 | 3001 | Amazon |
191+
| 512 | Delivered | 113 | 3001 | Amazon |
192+
| 984 | Processing | 54 | 3012 | Store |
193+
| 566 | Delivered | 850 | 3120 | Store |
194+
| 432 | Shipped | 99 | 3003 | Amazon |
195+
196+
197+
<details>
198+
<summary>Answer</summary>
199+
<ul>
200+
<li>Use the <code>ALTER TABLE</code> statement with <code>DROP COLUMN</code> to remove the column:</li>
201+
</ul>
202+
203+
```sql
204+
ALTER TABLE orders
205+
DROP COLUMN place_of_order;
206+
SELECT * FROM orders;
207+
```
208+
</details>
209+
---
210+
211+
#### 2. How can you add a new column called `discount` of type `int` to the `orders` table in SQL?
212+
213+
Here is the original `orders` table:
214+
215+
| order_no | order_status | order_amt | customer_id | place_of_order |
216+
|----------|--------------|-----------|-------------|----------------|
217+
| 101 | Delivered | 550 | 3001 | Amazon |
218+
| 512 | Delivered | 113 | 3001 | Amazon |
219+
| 984 | Processing | 54 | 3012 | Store |
220+
| 566 | Delivered | 850 | 3120 | Store |
221+
| 432 | Shipped | 99 | 3003 | Amazon |
222+
223+
<details>
224+
<summary>Answer</summary>
225+
<ul>
226+
<li>Use the <code>ALTER TABLE</code> statement with <code>ADD</code> to add the new column:</li>
227+
</ul>
228+
229+
```sql
230+
ALTER TABLE orders ADD discount int;
231+
SELECT * FROM orders;
232+
```
233+
</details>
234+
235+
<GiscusComments/>

0 commit comments

Comments
 (0)