How do I display all the contents of a table without duplicates?
Example:
Table 1
______________________
| ID | VALUE |
| 0 | A |
| 1 | A |
| 2 | B |
| 3 | C |
Expected output:
A
B
C
What about
SELECT DISTINCT VALUE FROM table
or use GROUP BY statement with VALUE column
there is not any duplicate rows. you can use distinct keyword only with values like
SELECT DISTINCT VALUE FROM XYZ;
you can do the same using group by
SELECT VALUE FROM XYZ GROUP BY VALUE;
but this is bullshit. a good developer will not use it.
Related
I have a MySQL table which has the following columns and records:
| Name | Total | GivenBy |
| ---- | -------- | ------------ |
| Z | 200 |['A','B','C'] |
| X | 240 |['A','D','C'] |
I would like to extract Record No. 1 on the basis of 3rd column where the SQL query would be like:
SELECT * FROM mytable WHERE GivenBy='B';
Is there a way I can loop through the list in third column and take out the respective string as required in the SQL WHERE clause in a single query?
Please note that I cannot add more columns in the table.
If you can please provide the query as MySQL compatible, I would really appreciate it.
The "array" you show isn't quite valid JSON, but if you use double-quotes instead of single-quotes, you can use JSON_TABLE() to do this:
CREATE TABLE MyTable
(
Name CHAR(1) PRIMARY KEY,
Total INT NOT NULL,
GivenBy JSON NOT NULL
);
INSERT INTO MyTable VALUES
('Z', 200, '["A","B","C"]'),
('X', 240, '["A","D","C"]');
SELECT Name, Total, g.Value
FROM MyTable
CROSS JOIN JSON_TABLE(GivenBy, '$[*]' COLUMNS(Value CHAR(1) PATH '$')) AS g;
+------+-------+-------+
| name | total | value |
+------+-------+-------+
| X | 240 | A |
| X | 240 | D |
| X | 240 | C |
| Z | 200 | A |
| Z | 200 | B |
| Z | 200 | C |
+------+-------+-------+
But the best choice is not to store "arrays" in MySQL. Store the values one per row in a second table.
You can use the "like" keyword with regex to match your requirements in the third column.
select * from table where givenBy like "%B%";
Something similar would work.
You need to run a script:
Retrieve the list of unique values in the GivenBy column using the following query:
SELECT DISTINCT JSON_EXTRACT(GivenBy, '$[*]') AS GivenByValues
FROM mytable;
Loop through the list of unique values, and for each value, run a query that uses that value in the WHERE clause:
SELECT *
FROM mytable
WHERE JSON_SEARCH(GivenBy, 'one', [current_value_from_loop]) IS NOT NULL;
I have a record table and its comment table, like:
| commentId | relatedRecordId | isRead |
|-----------+-----------------+--------|
| 1 | 1 | TRUE |
| 2 | 1 | FALSE |
| 3 | 1 | FALSE |
Now I want to select newCommentCount and allCommentCount as a server response to the browser. Is there any way to select these two fields in one SQL?
I've tried this:
SELECT `isRead`, count(*) AS cnt FROM comment WHERE relatedRecordId=1 GROUP BY `isRead`
| isRead | cnt |
| FALSE | 2 |
| TRUE | 1 |
But, I have to use a special data structure to map it and sum the cnt fields in two rows to get allCommentCount by using an upper-layer programming language. I want to know if I could get the following format of data by SQL only and in one step:
| newCommentCount | allCommentCount |
|-----------------+-----------------|
| 2 | 3 |
I don't even know how to describe the question. So I got no any search result in Google and Stackoverflow. (Because of My poor English, maybe)
Use conditional aggregation:
SELECT SUM(NOT isRead) AS newCommentCount, COUNT(*) AS allCommentCount
FROM comment
WHERE relatedRecordId = 1;
if I under stand you want show sum of newComments Count and all comments so you can do it like
SELECT SUM ( CASE WHEN isRead=false THEN 1 ELSE 0 END ) AS newComment,
Count(*) AS AllComments From comments where relatedRecord=1
also you can make store procedure for it.
To place two result sets horizontally, you can as simple as use a subquery for an expression in the SELECT CLAUSE as long as the number of rows from the result sets match:
select (select count(*) from c_table where isread=false and relatedRecordId=1 ) as newCommentCount,
count(*) as allCommentCount
from c_table where relatedRecordId=1;
I have two mysql tables record_items,property_values with the following structure.
table : property_values (column REC is foreign key to record_items)
id(PK)|REC(FK)| property | value|
1 | 1 | name | A |
2 | 1 | age | 10 |
3 | 2 | name | B |
4 | 3 | name | C |
5 | 3 | age | 9 |
table: record_items
id(PK) |col1|col2 |col3|
1 | v11| v12 | v13|
2 | v21| v22 | v23|
3 | v31| v32 | v33|
4 | v41| v42 | v43|
5 | v51| v52 | v53|
record_items table contains only basic information about the record, where as property_values table keeps record_item as a foreign key and each property and its value is saved in a separate row.
Now I want to get the record_items sorted based on a particular property, say by age.
My HQL query will be like
Select distinct rec from PropertyValues where property="age" order by value;
But this query will be skipping record 2 since it don't have an entry for property age.
I expect the result to have the records which contains age property in sort order appended by those which don't have age property at all. How can I query that?
Here is a raw MySQL query which should do the trick:
SELECT t1.*
FROM record_items t1
LEFT JOIN property_values t2
ON t1.id = t2.REC AND
t2.property = 'age'
ORDER BY CASE WHEN t2.value IS NULL THEN 1 ELSE 0 END, t2.Value
I notice that your Value column in property_values is mixing numeric and text data. This won't work well for sorting purposes.
Demo here
I have 2 table and there's a column which contains comma separated value and I want to count all same value of that column, here's the sample table:
Client table
ID | Name | Procedure
1 | Joe | Samp1,Samp2
2 | Doe | Samp1,Samp2,Samp3
3 | Noe | Samp1,Samp2
Desire Output
Summary table ( For Procedure )
ID | NAME | COUNT
1 | Samp1 | 3
2 | Samp2 | 3
3 | Samp3 | 1
Now, do you have any idea or suggestion so i can make it happen ? like add new table or is this possible with single query ?
Try this query
SELECT LENGTH(COLUMN) - LENGTH(REPLACE(COLUMN, ',', '')) FROM TABLE_NAME
I need to have a SQL that finds values from table B using (randomize) values on table A in comparative manner. Table A values has been produces in randomize manner. Table B values have been order in a way of cumulative distribution function. What is needed is that SQL will get the first row from table B which satisfy the criteria.
Table A:
+----+-------+
| ID | value |
+----+-------+
| 1 | 0.1234|
| 2 | 0.8923|
| 3 | 0.5221|
+----+-------+
Table B:
+----+-------+------+
| ID | value | name |
+----+-------+------+
| 1 | 0.2000| Alpha|
| 2 | 0.5000| Beta |
| 3 | 0.7500| Gamma|
| 4 | 1.0000| Delta|
+----+-------+------+
Result should be:
+----+-------+------+
| ID | value | name |
+----+-------+------+
| 1 | 0.1234| Alpha|
| 2 | 0.8923| Delta|
| 3 | 0.5221| Gamma|
+----+-------+------+
Value 0.1234 is smaller than all the values of B, but Alpha has smallest value.
Value 0.8923 is smaller than 1.000 --> Delta.
Value 0.5221 is smaller than both 0.7500 and 1.000 but 0.7500 is smallest --> Gamma.
This query works only if table A has one value:
select value, name
from B
where (select value from A) < value;
Any ideas how to get this work with full table A?
You can use subquery to get the data you need:
SELECT a.ID, a.value,
(SELECT b.name FROM TableB b WHERE a.value < b.value ORDER BY b.ID ASC LIMIT 1) as name
FROM TableA a
In this case for each row in table A you find the first record in table B, that has larger number in column value. Depending on your requirements the operator < might beed to be updated to <= - it depends on your requirements