mysql query to group duplicate records with a different field
1
I have a table T1 with columns id, C1, C2 and C3. I am using the following query to find duplicate records
Select group_concat(id) from T1 group by C2 having count(id) >1;
Now I want to group all the duplicate records by column C3. How do I do it?
Note : I am not expecting
Select group_concat(id) from T1 group by C2,C3 having count(id) >1;
I want to get all the records having duplicate values on C2 and group them only based on C3 irrespective of their C2 value
id C1 C2 C3
1 a 3 A
2 b 2 A
3 c 2 A
4 d 2 B
5 e 3 C
In the above data 1,5 are duplicate record with C2 value 3 and 2,3,4 is duplciate records with C2 value 2. I want an output
A - has 2 duplicates (with C2 values 2 and 3 )
B - has 1 duplicate (with C2 value 2)
C - has 1 duplicate (with C2 value 3)
mysql
asked Nov 12 '18 at 8:16
Jerry
373220
add a comment |
1
I have a table T1 with columns id, C1, C2 and C3. I am using the following query to find duplicate records
Select group_concat(id) from T1 group by C2 having count(id) >1;
Now I want to group all the duplicate records by column C3. How do I do it?
Note : I am not expecting
Select group_concat(id) from T1 group by C2,C3 having count(id) >1;
I want to get all the records having duplicate values on C2 and group them only based on C3 irrespective of their C2 value
id C1 C2 C3
1 a 3 A
2 b 2 A
3 c 2 A
4 d 2 B
5 e 3 C
In the above data 1,5 are duplicate record with C2 value 3 and 2,3,4 is duplciate records with C2 value 2. I want an output
A - has 2 duplicates (with C2 values 2 and 3 )
B - has 1 duplicate (with C2 value 2)
C - has 1 duplicate (with C2 value 3)
mysql
asked Nov 12 '18 at 8:16
Jerry
373220
Help us help you - please share some sample data and the result you're trying to get for it.
– Mureinik
Nov 12 '18 at 8:23
add a comment |
1
1
1
I have a table T1 with columns id, C1, C2 and C3. I am using the following query to find duplicate records
Select group_concat(id) from T1 group by C2 having count(id) >1;
Now I want to group all the duplicate records by column C3. How do I do it?
Note : I am not expecting
Select group_concat(id) from T1 group by C2,C3 having count(id) >1;
I want to get all the records having duplicate values on C2 and group them only based on C3 irrespective of their C2 value
id C1 C2 C3
1 a 3 A
2 b 2 A
3 c 2 A
4 d 2 B
5 e 3 C
In the above data 1,5 are duplicate record with C2 value 3 and 2,3,4 is duplciate records with C2 value 2. I want an output
A - has 2 duplicates (with C2 values 2 and 3 )
B - has 1 duplicate (with C2 value 2)
C - has 1 duplicate (with C2 value 3)
mysql
asked Nov 12 '18 at 8:16
Jerry
373220
I have a table T1 with columns id, C1, C2 and C3. I am using the following query to find duplicate records
Select group_concat(id) from T1 group by C2 having count(id) >1;
Now I want to group all the duplicate records by column C3. How do I do it?
Note : I am not expecting
Select group_concat(id) from T1 group by C2,C3 having count(id) >1;
I want to get all the records having duplicate values on C2 and group them only based on C3 irrespective of their C2 value
id C1 C2 C3
1 a 3 A
2 b 2 A
3 c 2 A
4 d 2 B
5 e 3 C
In the above data 1,5 are duplicate record with C2 value 3 and 2,3,4 is duplciate records with C2 value 2. I want an output
A - has 2 duplicates (with C2 values 2 and 3 )
B - has 1 duplicate (with C2 value 2)
C - has 1 duplicate (with C2 value 3)
mysql
mysql
asked Nov 12 '18 at 8:16
Jerry
373220
asked Nov 12 '18 at 8:16
Jerry
373220
edited Nov 12 '18 at 8:25
asked Nov 12 '18 at 8:16
Jerry
373220
asked Nov 12 '18 at 8:16
Jerry
373220
asked Nov 12 '18 at 8:16
Jerry
373220
373220
Help us help you - please share some sample data and the result you're trying to get for it.
– Mureinik
Nov 12 '18 at 8:23
add a comment |
Help us help you - please share some sample data and the result you're trying to get for it.
– Mureinik
Nov 12 '18 at 8:23
Help us help you - please share some sample data and the result you're trying to get for it.
– Mureinik
Nov 12 '18 at 8:23
Help us help you - please share some sample data and the result you're trying to get for it.
– Mureinik
Nov 12 '18 at 8:23
add a comment |
2 Answers
2
active
oldest
votes
1
- In a Derived Table, we can
GROUP BYonC2and identify their count(s).C2value having count more than 1 is basically a duplicate (occurring in more than one row). - Join this result-set to the main table on
C2. This will help us in getting an additional column showingC2count against every row. - Now, we can use conditional aggregation on
C3usingCOUNT(DISTINCT ...), considering those cases where count is more than 1.
Try:
SELECT
t.C3,
COUNT(DISTINCT IF(dt.count_C2 > 1, t.C2, NULL)) AS duplicates
FROM
your_table AS t
JOIN
(
SELECT
C2,
COUNT(id) AS count_C2
FROM your_table
GROUP BY C2
) AS dt
ON dt.C2 = t.C2
GROUP BY t.C3
Result
| C3 | duplicates |
| --- | ---------- |
| A | 2 |
| B | 1 |
| C | 1 |
View on DB Fiddle
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
add a comment |
1
SELECT GROUP_CONCAT(id)
FROM T1
WHERE C2 IN
(
SELECT C2
FROM T1
GROUP BY C2
HAVING COUNT(id)>1
)
GROUP BY C3
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
- In a Derived Table, we can
GROUP BYonC2and identify their count(s).C2value having count more than 1 is basically a duplicate (occurring in more than one row). - Join this result-set to the main table on
C2. This will help us in getting an additional column showingC2count against every row. - Now, we can use conditional aggregation on
C3usingCOUNT(DISTINCT ...), considering those cases where count is more than 1.
Try:
SELECT
t.C3,
COUNT(DISTINCT IF(dt.count_C2 > 1, t.C2, NULL)) AS duplicates
FROM
your_table AS t
JOIN
(
SELECT
C2,
COUNT(id) AS count_C2
FROM your_table
GROUP BY C2
) AS dt
ON dt.C2 = t.C2
GROUP BY t.C3
Result
| C3 | duplicates |
| --- | ---------- |
| A | 2 |
| B | 1 |
| C | 1 |
View on DB Fiddle
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
add a comment |
1
- In a Derived Table, we can
GROUP BYonC2and identify their count(s).C2value having count more than 1 is basically a duplicate (occurring in more than one row). - Join this result-set to the main table on
C2. This will help us in getting an additional column showingC2count against every row. - Now, we can use conditional aggregation on
C3usingCOUNT(DISTINCT ...), considering those cases where count is more than 1.
Try:
SELECT
t.C3,
COUNT(DISTINCT IF(dt.count_C2 > 1, t.C2, NULL)) AS duplicates
FROM
your_table AS t
JOIN
(
SELECT
C2,
COUNT(id) AS count_C2
FROM your_table
GROUP BY C2
) AS dt
ON dt.C2 = t.C2
GROUP BY t.C3
Result
| C3 | duplicates |
| --- | ---------- |
| A | 2 |
| B | 1 |
| C | 1 |
View on DB Fiddle
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
add a comment |
1
1
1
- In a Derived Table, we can
GROUP BYonC2and identify their count(s).C2value having count more than 1 is basically a duplicate (occurring in more than one row). - Join this result-set to the main table on
C2. This will help us in getting an additional column showingC2count against every row. - Now, we can use conditional aggregation on
C3usingCOUNT(DISTINCT ...), considering those cases where count is more than 1.
Try:
SELECT
t.C3,
COUNT(DISTINCT IF(dt.count_C2 > 1, t.C2, NULL)) AS duplicates
FROM
your_table AS t
JOIN
(
SELECT
C2,
COUNT(id) AS count_C2
FROM your_table
GROUP BY C2
) AS dt
ON dt.C2 = t.C2
GROUP BY t.C3
Result
| C3 | duplicates |
| --- | ---------- |
| A | 2 |
| B | 1 |
| C | 1 |
View on DB Fiddle
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
- In a Derived Table, we can
GROUP BYonC2and identify their count(s).C2value having count more than 1 is basically a duplicate (occurring in more than one row). - Join this result-set to the main table on
C2. This will help us in getting an additional column showingC2count against every row. - Now, we can use conditional aggregation on
C3usingCOUNT(DISTINCT ...), considering those cases where count is more than 1.
Try:
SELECT
t.C3,
COUNT(DISTINCT IF(dt.count_C2 > 1, t.C2, NULL)) AS duplicates
FROM
your_table AS t
JOIN
(
SELECT
C2,
COUNT(id) AS count_C2
FROM your_table
GROUP BY C2
) AS dt
ON dt.C2 = t.C2
GROUP BY t.C3
Result
| C3 | duplicates |
| --- | ---------- |
| A | 2 |
| B | 1 |
| C | 1 |
View on DB Fiddle
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
edited Nov 12 '18 at 8:59
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
answered Nov 12 '18 at 8:43
Madhur Bhaiya
19.5k62236
19.5k62236
add a comment |
add a comment |
1
SELECT GROUP_CONCAT(id)
FROM T1
WHERE C2 IN
(
SELECT C2
FROM T1
GROUP BY C2
HAVING COUNT(id)>1
)
GROUP BY C3
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
add a comment |
1
SELECT GROUP_CONCAT(id)
FROM T1
WHERE C2 IN
(
SELECT C2
FROM T1
GROUP BY C2
HAVING COUNT(id)>1
)
GROUP BY C3
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
add a comment |
1
1
1
SELECT GROUP_CONCAT(id)
FROM T1
WHERE C2 IN
(
SELECT C2
FROM T1
GROUP BY C2
HAVING COUNT(id)>1
)
GROUP BY C3
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
SELECT GROUP_CONCAT(id)
FROM T1
WHERE C2 IN
(
SELECT C2
FROM T1
GROUP BY C2
HAVING COUNT(id)>1
)
GROUP BY C3
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
answered Nov 12 '18 at 8:29
sbrbot
2,92112144
2,92112144
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
add a comment |
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
what if my first group by is with multiple properties, say Group by C2,C1
– Jerry
Nov 12 '18 at 8:35
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
@Jerry what if you try and check what happens? If that is a valid use case, you should have mentioned it before
– Nico Haase
Nov 12 '18 at 9:02
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
I can have multiple where clauses that case, is that an optimal way to achieve this?
– Jerry
Nov 12 '18 at 9:41
add a comment |
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Help us help you - please share some sample data and the result you're trying to get for it.
– Mureinik
Nov 12 '18 at 8:23