mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-15 02:41:59 +00:00
158 lines
4.8 KiB
Markdown
158 lines
4.8 KiB
Markdown
---
|
|
slug: /en/sql-reference/statements/select/intersect
|
|
sidebar_label: INTERSECT
|
|
---
|
|
|
|
# INTERSECT Clause
|
|
|
|
The `INTERSECT` clause returns only those rows that result from both the first and the second queries. The queries must match the number of columns, order, and type. The result of `INTERSECT` can contain duplicate rows.
|
|
|
|
Multiple `INTERSECT` statements are executed left to right if parentheses are not specified. The `INTERSECT` operator has a higher priority than the `UNION` and `EXCEPT` clauses.
|
|
|
|
|
|
``` sql
|
|
SELECT column1 [, column2 ]
|
|
FROM table1
|
|
[WHERE condition]
|
|
|
|
INTERSECT
|
|
|
|
SELECT column1 [, column2 ]
|
|
FROM table2
|
|
[WHERE condition]
|
|
|
|
```
|
|
The condition could be any expression based on your requirements.
|
|
|
|
## Examples
|
|
|
|
Here is a simple example that intersects the numbers 1 to 10 with the numbers 3 to 8:
|
|
|
|
```sql
|
|
SELECT number FROM numbers(1,10) INTERSECT SELECT number FROM numbers(3,8);
|
|
```
|
|
|
|
Result:
|
|
|
|
```response
|
|
┌─number─┐
|
|
│ 3 │
|
|
│ 4 │
|
|
│ 5 │
|
|
│ 6 │
|
|
│ 7 │
|
|
│ 8 │
|
|
└────────┘
|
|
```
|
|
|
|
`INTERSECT` is useful if you have two tables that share a common column (or columns). You can intersect the results of two queries, as long as the results contain the same columns. For example, suppose we have a few million rows of historical cryptocurrency data that contains trade prices and volume:
|
|
|
|
```sql
|
|
CREATE TABLE crypto_prices
|
|
(
|
|
trade_date Date,
|
|
crypto_name String,
|
|
volume Float32,
|
|
price Float32,
|
|
market_cap Float32,
|
|
change_1_day Float32
|
|
)
|
|
ENGINE = MergeTree
|
|
PRIMARY KEY (crypto_name, trade_date);
|
|
|
|
INSERT INTO crypto_prices
|
|
SELECT *
|
|
FROM s3(
|
|
'https://learn-clickhouse.s3.us-east-2.amazonaws.com/crypto_prices.csv',
|
|
'CSVWithNames'
|
|
);
|
|
|
|
SELECT * FROM crypto_prices
|
|
WHERE crypto_name = 'Bitcoin'
|
|
ORDER BY trade_date DESC
|
|
LIMIT 10;
|
|
```
|
|
|
|
```response
|
|
┌─trade_date─┬─crypto_name─┬──────volume─┬────price─┬───market_cap─┬──change_1_day─┐
|
|
│ 2020-11-02 │ Bitcoin │ 30771456000 │ 13550.49 │ 251119860000 │ -0.013585099 │
|
|
│ 2020-11-01 │ Bitcoin │ 24453857000 │ 13737.11 │ 254569760000 │ -0.0031840964 │
|
|
│ 2020-10-31 │ Bitcoin │ 30306464000 │ 13780.99 │ 255372070000 │ 0.017308505 │
|
|
│ 2020-10-30 │ Bitcoin │ 30581486000 │ 13546.52 │ 251018150000 │ 0.008084608 │
|
|
│ 2020-10-29 │ Bitcoin │ 56499500000 │ 13437.88 │ 248995320000 │ 0.012552661 │
|
|
│ 2020-10-28 │ Bitcoin │ 35867320000 │ 13271.29 │ 245899820000 │ -0.02804481 │
|
|
│ 2020-10-27 │ Bitcoin │ 33749879000 │ 13654.22 │ 252985950000 │ 0.04427984 │
|
|
│ 2020-10-26 │ Bitcoin │ 29461459000 │ 13075.25 │ 242251000000 │ 0.0033826586 │
|
|
│ 2020-10-25 │ Bitcoin │ 24406921000 │ 13031.17 │ 241425220000 │ -0.0058658565 │
|
|
│ 2020-10-24 │ Bitcoin │ 24542319000 │ 13108.06 │ 242839880000 │ 0.013650347 │
|
|
└────────────┴─────────────┴─────────────┴──────────┴──────────────┴───────────────┘
|
|
```
|
|
|
|
Now suppose we have a table named `holdings` that contains a list of cryptocurrencies that we own, along with the number of coins:
|
|
|
|
```sql
|
|
CREATE TABLE holdings
|
|
(
|
|
crypto_name String,
|
|
quantity UInt64
|
|
)
|
|
ENGINE = MergeTree
|
|
PRIMARY KEY (crypto_name);
|
|
|
|
INSERT INTO holdings VALUES
|
|
('Bitcoin', 1000),
|
|
('Bitcoin', 200),
|
|
('Ethereum', 250),
|
|
('Ethereum', 5000),
|
|
('DOGEFI', 10);
|
|
('Bitcoin Diamond', 5000);
|
|
```
|
|
|
|
We can use `INTERSECT` to answer questions like **"Which coins do we own that have traded at a price greater than $100?"**:
|
|
|
|
```sql
|
|
SELECT crypto_name FROM holdings
|
|
INTERSECT
|
|
SELECT crypto_name FROM crypto_prices
|
|
WHERE price > 100
|
|
```
|
|
|
|
Result:
|
|
|
|
```response
|
|
┌─crypto_name─┐
|
|
│ Bitcoin │
|
|
│ Bitcoin │
|
|
│ Ethereum │
|
|
│ Ethereum │
|
|
└─────────────┘
|
|
```
|
|
|
|
This means at some point in time, Bitcoin and Ethereum traded above $100, and DOGEFI and Bitcoin Diamond have never traded above $100 (at least using the data we have here in this example).
|
|
|
|
## INTERSECT DISTINCT
|
|
|
|
Notice in the previous query we had multiple Bitcoin and Ethereum holdings that traded above $100. It might be nice to remove duplicate rows (since they only repeat what we already know). You can add `DISTINCT` to `INTERSECT` to eliminate duplicate rows from the result:
|
|
|
|
```sql
|
|
SELECT crypto_name FROM holdings
|
|
INTERSECT DISTINCT
|
|
SELECT crypto_name FROM crypto_prices
|
|
WHERE price > 100;
|
|
```
|
|
|
|
Result:
|
|
|
|
```response
|
|
┌─crypto_name─┐
|
|
│ Bitcoin │
|
|
│ Ethereum │
|
|
└─────────────┘
|
|
```
|
|
|
|
|
|
**See Also**
|
|
|
|
- [UNION](union.md#union-clause)
|
|
- [EXCEPT](except.md#except-clause)
|