This is difficult one to explain, so I'll do my best.
I have this table (other cols exist but irrelevant to my query).
CREATE TABLE ClientRelationships
(
Client1 VARCHAR(10) NOT NULL,
Client2 VARCHAR(10) NULL
)
INSERT INTO ClientRelationships (Client1, Client2)
VALUES ('C12345', 'C67890'),
('C54353', 'C76345'),
('C76345', 'C54353'),
('C73246', NULL),
('C67890', 'C12345')
Client1
Client2
C12345
C67890
C54353
C76345
C76345
C54353
C73246
NULL
C67890
C12345
As you can see from the data, there are rows where the Client1 value appears in another row as Client2. In these instances, what I am looking to do mark the first occurrence as "Primary" and the second occurrence as "Secondary" (where the Client1 value is in the Client2 column on a different row). Maybe just as a boolean column called "Primary" set to 0 or 1.
Where there is no value in the Client2 column (NULL) the Primary column would be set to 1
Result would hopefully look like this with my example data.
Client1
Client2
Primary
C12345
C67890
1
C54353
C76345
1
C76345
C54353
0
C73246
NULL
1
C67890
C12345
0
Hope this makes sense.
I'm using SQL Server 2019, but anything from 2012 and above can be catered for as I have instances of all.
The records do not always appear concurrently in the table.
I am really unsure how to approach this so looking for some advice.
If there is column that defines the order of the rows, like an ID, then you can do it with a CASE expression and EXISTS:
SELECT c1.*,
CASE
WHEN EXISTS(SELECT 1 FROM ClientRelationships c2 WHERE c2.ID < c1.ID AND c2.Client2 = c1.Client1) THEN 0
ELSE 1
END [Primary]
FROM ClientRelationships c1
Or, with a correlated subquery:
SELECT c1.*,
(
SELECT COALESCE(MAX(0), 1)
FROM ClientRelationships c2
WHERE c2.ID < c1.ID AND c2.Client2 = c1.Client1
) [Primary]
FROM ClientRelationships c1
See the demo.
I have a table with ID column
ID column is like this : IDxxxxyyy
x will be 0 to 9
I have to select row with ID like ID0xxx% to ID3xxx%, there will be around 4000 ID with % wildcard from ID0000% to ID3999%.
It is like combining LIKE with IN
Select * from TABLE where ID in (ID0000%,ID0001%,...,ID3999%)
I cannot figure out how to select with this condition.
If you have any idea, please help.
Thank you so much!
You can use pattern matching with LIKE. e.g.
WHERE ID LIKE 'ID[0-3][0-9][0-9][0-9]%'
Will match an string that:
Starts with ID (ID)
Then has a third character that is a number between 0 and 3 [0-3]
Then has 3 further numbers ([0-9][0-9][0-9])
This is not likely to perform well at all. If it is not too late to alter your table design, I would separate out the components of your Identifier and store them separately, then use a computed column to store your full id e.g.
CREATE TABLE T
(
NumericID INT NOT NULL,
YYY CHAR(3) NOT NULL, -- Or whatever type makes up yyy in your ID
FullID AS CONCAT('ID', FORMAT(NumericID, '0000'), YYY),
CONSTRAINT PK_T__NumericID_YYY PRIMARY KEY (NumericID, YYY)
);
Then your query is a simple as:
SELECT FullID
FROM T
WHERE NumericID >= 0
AND NumericID < 4000;
This is significantly easier to read and write, and will be significantly faster too.
This should do that, it will get all the IDs that start with IDx, with x that goes form 0 to 4
Select * from TABLE where ID LIKE 'ID[0-4]%'
You can try :
Select * from TABLE where id like 'ID[0-3][0-9]%[a-zA-Z]';
scenario:
Sql Server 2012 Table named "Test" has two fields. "CounterNo" and "Value" both integers.
There are 4 sequence objects defined named sq1, sq2, sq3, sq4
I want to do these on inserts:
if CounterNo = 1 then Value = next value for sq1
if CounterNo = 2 then Value = next value for sq2
if CounterNo = 3 then Value = next value for sq3
I think, create a custom function assign it as default value of Value field. But when i tried custom functions not supports "next value for Sequence Objects"
Another way is using trigger. That table has trigger already.
Using a Stored Procedure for Inserts is the best way. But EntityFramework 5 Code-First is not supporting it.
Can you suggest me a way to achieve this.
(if you show me how can i do it with custom functions you can also post it here. It's another question of me.)
Update:
In reality there are 23 fields in that table and also primary keys setted and i'm generating this counter value on software side, using "counter table".It is not good to generate counter values on client side.
I'm using 4 sequence objects as counters because they represents different types of records.
If i use 4 counters on same record at same time, all of them generates next values. I want only related counter generates it's next value while others remains same.
I'm not shure if I fully understand your use case but maybe the following sample illustrates what you need.
Create Table Vouchers (
Id uniqueidentifier Not Null Default NewId()
, Discriminator varchar(100) Not Null
, VoucherNumber int Null
-- ...
, MoreData nvarchar(100) Null
);
go
Create Sequence InvoiceSequence AS int Start With 1 Increment By 1;
Create Sequence OrderSequence AS int Start With 1 Increment By 1;
go
Create Trigger TR_Voucher_Insert_VoucherNumer On Vouchers After Insert As
If Exists (Select 1 From inserted Where Discriminator = 'Invoice')
Update v
Set VoucherNumber = Next Value For InvoiceSequence
From Vouchers v Inner Join inserted i On (v.Id = i.Id)
Where i.Discriminator = 'Invoice';
If Exists (Select 1 From inserted Where Discriminator = 'Order')
Update v
Set VoucherNumber = Next Value For OrderSequence
From Vouchers v Inner Join inserted i On (v.Id = i.Id)
Where i.Discriminator = 'Order';
go
Insert Into Vouchers (Discriminator, MoreData)
Values ('Invoice', 'Much')
, ('Invoice', 'More')
, ('Order', 'Data')
, ('Invoice', 'And')
, ('Order', 'Again')
;
go
Select * From Vouchers;
Now Invoice- and Order-Numbers will be incremented independently. And as you can have multiple insert triggers on the same table, that shouldn't be an issue.
I think you're thinking about this in the wrong way. You have 3 values and these values are determined by another column. Switch it around, create 3 columns and remove the Counter column.
If you have a table with value1, value2 and value3 then the Counter value is implied by the column in which the value resides. Create a unique index on these three columns and add an identity column for a primary key and you're sorted; you can do it all in a stored procedure easily.
If you have four different types of records, use four different tables, with a separate identity column in each one.
If you need to see all the data together, then use a view to combine them:
create v_AllTypes as
select * from type1 union all
select * from type2 union all
select * from type3 union all
select * from type4;
Alternatively, do the calculation of the sequence number on output:
select t.*,
row_number() over (partition by CounterNo order by t.id) as TypeSeqNum
from AllTypes t;
Something seems amiss with your data model if it requires conditional updates to four identity columns.
I need to perform UPSERT / INSERT OR UPDATE against a SQLite Database.
There is the command INSERT OR REPLACE which in many cases can be useful. But if you want to keep your id's with autoincrement in place because of foreign keys, it does not work since it deletes the row, creates a new one and consequently this new row has a new ID.
This would be the table:
players - (primary key on id, user_name unique)
| id | user_name | age |
------------------------------
| 1982 | johnny | 23 |
| 1983 | steven | 29 |
| 1984 | pepee | 40 |
Q&A Style
Well, after researching and fighting with the problem for hours, I found out that there are two ways to accomplish this, depending on the structure of your table and if you have foreign keys restrictions activated to maintain integrity. I'd like to share this in a clean format to save some time to the people that may be in my situation.
Option 1: You can afford deleting the row
In other words, you don't have foreign key, or if you have them, your SQLite engine is configured so that there no are integrity exceptions. The way to go is INSERT OR REPLACE. If you are trying to insert/update a player whose ID already exists, the SQLite engine will delete that row and insert the data you are providing. Now the question comes: what to do to keep the old ID associated?
Let's say we want to UPSERT with the data user_name='steven' and age=32.
Look at this code:
INSERT INTO players (id, name, age)
VALUES (
coalesce((select id from players where user_name='steven'),
(select max(id) from drawings) + 1),
32)
The trick is in coalesce. It returns the id of the user 'steven' if any, and otherwise, it returns a new fresh id.
Option 2: You cannot afford deleting the row
After monkeying around with the previous solution, I realized that in my case that could end up destroying data, since this ID works as a foreign key for other table. Besides, I created the table with the clause ON DELETE CASCADE, which would mean that it'd delete data silently. Dangerous.
So, I first thought of a IF clause, but SQLite only has CASE. And this CASE can't be used (or at least I did not manage it) to perform one UPDATE query if EXISTS(select id from players where user_name='steven'), and INSERT if it didn't. No go.
And then, finally I used the brute force, with success. The logic is, for each UPSERT that you want to perform, first execute a INSERT OR IGNORE to make sure there is a row with our user, and then execute an UPDATE query with exactly the same data you tried to insert.
Same data as before: user_name='steven' and age=32.
-- make sure it exists
INSERT OR IGNORE INTO players (user_name, age) VALUES ('steven', 32);
-- make sure it has the right data
UPDATE players SET user_name='steven', age=32 WHERE user_name='steven';
And that's all!
EDIT
As Andy has commented, trying to insert first and then update may lead to firing triggers more often than expected. This is not in my opinion a data safety issue, but it is true that firing unnecessary events makes little sense. Therefore, a improved solution would be:
-- Try to update any existing row
UPDATE players SET age=32 WHERE user_name='steven';
-- Make sure it exists
INSERT OR IGNORE INTO players (user_name, age) VALUES ('steven', 32);
This is a late answer. Starting from SQLIte 3.24.0, released on June 4, 2018, there is finally a support for UPSERT clause following PostgreSQL syntax.
INSERT INTO players (user_name, age)
VALUES('steven', 32)
ON CONFLICT(user_name)
DO UPDATE SET age=excluded.age;
Note: For those having to use a version of SQLite earlier than 3.24.0, please reference this answer below (posted by me, #MarqueIV).
However if you do have the option to upgrade, you are strongly encouraged to do so as unlike my solution, the one posted here achieves the desired behavior in a single statement. Plus you get all the other features, improvements and bug fixes that usually come with a more recent release.
Here's an approach that doesn't require the brute-force 'ignore' which would only work if there was a key violation. This way works based on any conditions you specify in the update.
Try this...
-- Try to update any existing row
UPDATE players
SET age=32
WHERE user_name='steven';
-- If no update happened (i.e. the row didn't exist) then insert one
INSERT INTO players (user_name, age)
SELECT 'steven', 32
WHERE (Select Changes() = 0);
How It Works
The 'magic sauce' here is using Changes() in the Where clause. Changes() represents the number of rows affected by the last operation, which in this case is the update.
In the above example, if there are no changes from the update (i.e. the record doesn't exist) then Changes() = 0 so the Where clause in the Insert statement evaluates to true and a new row is inserted with the specified data.
If the Update did update an existing row, then Changes() = 1 (or more accurately, not zero if more than one row was updated), so the 'Where' clause in the Insert now evaluates to false and thus no insert will take place.
The beauty of this is there's no brute-force needed, nor unnecessarily deleting, then re-inserting data which may result in messing up downstream keys in foreign-key relationships.
Additionally, since it's just a standard Where clause, it can be based on anything you define, not just key violations. Likewise, you can use Changes() in combination with anything else you want/need anywhere expressions are allowed.
The problem with all presented answers it complete lack of taking triggers (and probably other side effects) into account.
Solution like
INSERT OR IGNORE ...
UPDATE ...
leads to both triggers executed (for insert and then for update) when row does not exist.
Proper solution is
UPDATE OR IGNORE ...
INSERT OR IGNORE ...
in that case only one statement is executed (when row exists or not).
To have a pure UPSERT with no holes (for programmers) that don't relay on unique and other keys:
UPDATE players SET user_name="gil", age=32 WHERE user_name='george';
SELECT changes();
SELECT changes() will return the number of updates done in the last inquire.
Then check if return value from changes() is 0, if so execute:
INSERT INTO players (user_name, age) VALUES ('gil', 32);
Option 1: Insert -> Update
If you like to avoid both changes()=0 and INSERT OR IGNORE even if you cannot afford deleting the row - You can use this logic;
First, insert (if not exists) and then update by filtering with the unique key.
Example
-- Table structure
CREATE TABLE players (
id INTEGER PRIMARY KEY AUTOINCREMENT,
user_name VARCHAR (255) NOT NULL
UNIQUE,
age INTEGER NOT NULL
);
-- Insert if NOT exists
INSERT INTO players (user_name, age)
SELECT 'johnny', 20
WHERE NOT EXISTS (SELECT 1 FROM players WHERE user_name='johnny' AND age=20);
-- Update (will affect row, only if found)
-- no point to update user_name to 'johnny' since it's unique, and we filter by it as well
UPDATE players
SET age=20
WHERE user_name='johnny';
Regarding Triggers
Notice: I haven't tested it to see the which triggers are being called, but I assume the following:
if row does not exists
BEFORE INSERT
INSERT using INSTEAD OF
AFTER INSERT
BEFORE UPDATE
UPDATE using INSTEAD OF
AFTER UPDATE
if row does exists
BEFORE UPDATE
UPDATE using INSTEAD OF
AFTER UPDATE
Option 2: Insert or replace - keep your own ID
in this way you can have a single SQL command
-- Table structure
CREATE TABLE players (
id INTEGER PRIMARY KEY AUTOINCREMENT,
user_name VARCHAR (255) NOT NULL
UNIQUE,
age INTEGER NOT NULL
);
-- Single command to insert or update
INSERT OR REPLACE INTO players
(id, user_name, age)
VALUES ((SELECT id from players WHERE user_name='johnny' AND age=20),
'johnny',
20);
Edit: added option 2.
You can also just add an ON CONFLICT REPLACE clause to your user_name unique constraint and then just INSERT away, leaving it to SQLite to figure out what to do in case of a conflict. See:https://sqlite.org/lang_conflict.html.
Also note the sentence regarding delete triggers: When the REPLACE conflict resolution strategy deletes rows in order to satisfy a constraint, delete triggers fire if and only if recursive triggers are enabled.
For those who have the latest version of sqlite available, you can still do it in a single statement using INSERT OR REPLACE but beware you need to set all the values. However this "clever" SQL works by use of a left-join on the table into which you are inserting / updating and ifnull:
import sqlite3
con = sqlite3.connect( ":memory:" )
cur = con.cursor()
cur.execute("create table test( id varchar(20) PRIMARY KEY, value int, value2 int )")
cur.executemany("insert into test (id, value, value2) values (:id, :value, :value2)",
[ {'id': 'A', 'value' : 1, 'value2' : 8 }, {'id': 'B', 'value' : 3, 'value2' : 10 } ] )
cur.execute('select * from test')
print( cur.fetchall())
con.commit()
cur = con.cursor()
# upsert using insert or replace.
# when id is found it should modify value but ignore value2
# when id is not found it will enter a record with value and value2
upsert = '''
insert or replace into test
select d.id, d.value, ifnull(t.value2, d.value2) from ( select :id as id, :value as value, :value2 as value2 ) d
left join test t on d.id = t.id
'''
upsert_data = [ { 'id' : 'B', 'value' : 4, 'value2' : 5 },
{ 'id' : 'C', 'value' : 3, 'value2' : 12 } ]
cur.executemany( upsert, upsert_data )
cur.execute('select * from test')
print( cur.fetchall())
The first few lines of that code are setting up the table, with a single ID primary key column and two values. It then enters data with IDs 'A' and 'B'
The second section creates the 'upsert' text, and calls it for 2 rows of data, one with the ID of 'B' which is found and one with 'C' which is not found.
When you run it, you'll find the data at the end produces
$python3 main.py
[('A', 1, 8), ('B', 3, 10)]
[('A', 1, 8), ('B', 4, 10), ('C', 3, 12)]
B 'updated' value to 4 but value2 (5) was ignored, C inserted.
Note: this does not work if your table has an auto-incremented primary key as INSERT OR REPLACE will replace the number with a new one.
A slight modification to add such a column
import sqlite3
con = sqlite3.connect( ":memory:" )
cur = con.cursor()
cur.execute("create table test( pkey integer primary key autoincrement not null, id varchar(20) UNIQUE not null, value int, value2 int )")
cur.executemany("insert into test (id, value, value2) values (:id, :value, :value2)",
[ {'id': 'A', 'value' : 1, 'value2' : 8 }, {'id': 'B', 'value' : 3, 'value2' : 10 } ] )
cur.execute('select * from test')
print( cur.fetchall())
con.commit()
cur = con.cursor()
# upsert using insert or replace.
# when id is found it should modify value but ignore value2
# when id is not found it will enter a record with value and value2
upsert = '''
insert or replace into test (id, value, value2)
select d.id, d.value, ifnull(t.value2, d.value2) from ( select :id as id, :value as value, :value2 as value2 ) d
left join test t on d.id = t.id
'''
upsert_data = [ { 'id' : 'B', 'value' : 4, 'value2' : 5 },
{ 'id' : 'C', 'value' : 3, 'value2' : 12 } ]
cur.executemany( upsert, upsert_data )
cur.execute('select * from test')
print( cur.fetchall())
output is now:
$python3 main.py
[(1, 'A', 1, 8), (2, 'B', 3, 10)]
[(1, 'A', 1, 8), (3, 'B', 4, 10), (4, 'C', 3, 12)]
Note pkey 2 is replaced with 3 for id 'B'
This is therefore not ideal but is a good solution when:
You don't have an auto-generated primary key
You want to create an 'upsert' query with bound parameters
You want to use executemany() to merge in multiple rows of data in one go.
Suppose I have a table with following data:
gameId difficultyLevel numberOfQuestions
--------------------------------------------
1 1 2
1 2 2
1 3 1
In this example the game is configured for 5 questions, but I'm looking for a SQL statement that will work for n number of questions.
What I need is a SQL statement that given a question, displayOrder will return the current difficulty level of question. For example - given a displayOrder of 3, with the table data above, will return 2.
Can anyone advise how the query should look like?
I'd recommend a game table with a 1:m relationship with a question table.
You shouldn't repeat columns in a table - it violates first normal form.
Something like this:
create table if not exists game
(
game_id bigint not null auto_increment,
name varchar(64),
description varchar(64),
primary key (game_id)
);
create table if not exists question
(
question_id bigint not null auto_increment,
text varchar(64),
difficulty int default 1,
game_id bigint,
primary key (question_id) ,
foreign key game_id references game(game_id)
);
select
game.game_id, name, description, question_id, text, difficulty
game left join question
on game.game_id = question.game_id
order by question_id;
things might be easier for you if you change your design as duffymo suggests, but if you must do it that way, here's a query that should do the trick.
SELECT MIN(difficultyLevel) as difficltyLevel
FROM
(
SELECT difficltyLevel, (SELECT sum(numberOfQuestions) FROM yourtable sub WHERE sub.difficultyLevel <= yt.difficultyLevel ) AS questionTotal
FROM yourTable yt
) AS innerSQL
WHERE innerSQL.questionTotal >= #displayOrder