I have a MySQL table containing default and override values that, when simplified, looks like so:
create table t (
identifier varchar(20),
override varchar(20),
data1 int,
data2 varchar(2),
...
)
I want to get all items out of the table that have a blank in the override column. Unless there is a row with the same identifier and a non blank override. In that case I want the override to be returned instead.
I suspect I want to do something with GROUP BY to select the row but I can't figure out how to ensure I'm getting the right values in the datax columns.
Here is how I would achieve the solution ... perform a sub query on and get sameIdentifierWithOverride - this is the number of rows in the table with the same identifier but with an override that isn't empty. You can then use having to filter down the results ..
select *,
(select count(*) from t t2 where t2.identifier=t.identifier and t2.override != '') sameIdentifierWithOverride
from t where override='' having sameIdentifierWithOverride=0
Related
It's been my first question to this website, I'm sorry if I used any wrong keywords. I have been with one problem from quite a few days.
The Problem is, I have a MYSQL table named property where I wanted to add a ref number which will be a unique 6 digit non incremental number so I alter the table to add a new column named property_ref which has default value as 1.
ALTER TABLE property ADD uniqueIdentifier INT DEFAULT (1) ;
Then I write a script to first generate a number then checking it to db if exist or not and If not exist then update the row with the random number
Here is the snippet I tried,
with cte as (
select subIdentifier, id from (
SELECT id, LPAD(FLOOR(RAND() * (999999 - 100000) + 100000), 6, 0) AS subIdentifier
FROM property as p1
WHERE "subIdentifier" NOT IN (SELECT uniqueIdentifier FROM property as p2)
) as innerTable group by subIdentifier
)
UPDATE property SET uniqueIdentifier = (
select subIdentifier from cte as c where c.id = property.id
) where property.id != ''
this query returns a set of record for almost all the rows but I have a table of entries of total 20000,
but this query fills up for ~19000 and rest of the rows are null.
here is a current output
[current result picture]
If anyone can help, I am extremely thanks for that.
Thanks
Instead of trying to randomly generate unique numbers that do not exist in the table, I would try the approach of randomly generating numbers using the ID column as a seed; as long as the ID number is unique, the new number will be unique as well. This is not technically fully "random" but it may be sufficient for your needs.
https://www.db-fiddle.com/f/iqMPDK8AmdvAoTbon1Yn6J/1
update Property set
UniqueIdentifier = round(rand(id)*1000000)
where UniqueIdentifier is null
SELECT id, round(rand(id)*1000000) as UniqueIdentifier FROM test;
Im attempting to do a SELECT on data in a table that contains prefixes, and I have the "keyword".
So unlike a normal search where the prefix/keyword is contained in the row data, and that the prefix/keyword is shorter (or contained in) a possible row of data.
This is the opposite. If have prefixes in rows and I want to find the best matching row based on the (longer) word/phase.
CREATE TABLE table1 (id INT NOT NULL AUTO_INCREMENT, keyCode VARCHAR(45) NULL, Username VARCHAR(45) NULL, PRIMARY KEY (id));
INSERT INTO table1(keyCode,Username)VALUES('123','Peter')
INSERT INTO table1(keyCode,Username)VALUES('456','Paul')
INSERT INTO table1(keyCode,Username)VALUES('1234','John')
Now let's say the phrase I have been given is longer than the prefix in the data.
Like this:
SELECT * FROM table1 WHERE keyCode LIKE '123456%';
I know this will not work, but I would like to return the Row with User 'John'.
How?
(I can use stored procedures)
You may phrase your LIKE expression in the reverse order:
SELECT *
FROM table1
WHERE '123456' LIKE CONCAT(keyCode, '%');
This would compare, for example, '123456' against '1234%', which should be a match in this case.
You can check for the existence of the keyCode prefix at the beginning of your string using LOCATE(). For example:
SELECT *
FROM table1
WHERE LOCATE(keyCode,'123456') = 1;
I've got a SQL 2008 R2 table defined like this:
CREATE TABLE [dbo].[Search_Name](
[Id] [bigint] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](300) NULL),
CONSTRAINT [PK_Search_Name] PRIMARY KEY CLUSTERED ([Id] ASC))
Performance querying the Name field using CONTAINS and FREETEXT works well.
However, I'm trying to keep the values of my Name column unique. Searching for an existing entry in the Name column is unbelievably slow for a large number of names (usually batches of 1,000), even with an index on the Name field. Query plans indicate I'm using the index as expected.
To search for an existing value, my query looks like this:
SELECT TOP 1 Id, Name from Search_Name where Name = 'My Name Value'
I've tried duplicating the Name column to another column and searching on the new column, but the net effect was the same.
At this point, I'm thinking I must be mis-using this feature.
Should I just stop trying to prevent duplication? I'm using a linking table to join these search name values to the underlying data. It seems somehow 'dirty' to just store a whole bunch of duplicate values...
...or is there faster way to take a list of 1,000 names and see which ones are already stored in the database?
The first change to make is to get the entire list to SQL Server at one time. Regardless of how you add the names to the existing table, doing it as a set operation will make a big difference in performance.
Passing the List as a table-valued parameter (TVP) is a clean way to handle it. Have a look here for an example. You can still use an OUTPUT clause to track which rows did or didn't make the cut, for example:
-- Some sample existing names.
declare #Search_Name as Table ( Id Int Identity, Name VarChar(32) );
insert into #Search_Name ( Name ) values ( 'Bob' ), ( 'Carol' ), ( 'Ted' ), ( 'Alice' );
select * from #Search_Name;
-- Some (prospective) new names.
declare #New_Names as Table ( Name VarChar(32) );
insert into #New_Names ( Name ) values ( 'Ralph' ), ( 'Alice' ), ( 'Ed' ), ( 'Trixie' );
select * from #New_Names;
-- Add the unique new names.
declare #Inserted as Table ( Id Int, Name VarChar(32) );
insert into #Search_Name
output inserted.Id, inserted.Name into #Inserted
select New.Name
from #New_Names as New left outer join
#Search_Name as Old on Old.Name = New.Name
where Old.Id is NULL;
-- Results.
select * from #Search_Name;
-- The names that were added and their id's.
select * from #Inserted;
-- The names that were not added.
select New.Name
from #New_Names as New left outer join
#Inserted as I on I.Name = New.Name
where I.Id is NULL;
Alternatively, you could use a MERGE statement and OUTPUT the names that were added, those that weren't, or both.
I'm trying to create a simple table where I insert field and I do some checks in MySql. I've used Microsoft SQL relatively easy. Instead, MySql give evrrytime query errors without even specifying what's going on. Poor MySql software design apart, here's what I'm trying to do:
1 table with 4 fields with an autoincremental autogenerated number to det an ID as primary key
CREATE TABLE `my_db`.`Patients_table` (
`ID_Patient` INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY ,
`Patient_name` VARCHAR( 200 ) NOT NULL ,
`Recovery_Date` DATETIME NOT NULL ,
`Recovery_count` INT NOT NULL
) ENGINE = MYISAM
a simple stored procedure to insert such fields and check if something exist before inserting:
CREATE PROCEDURE nameInsert(IN nome, IN data)
INSERT INTO Patients_table (Patient_name,Recovery_Date) values (nome,data)
IF (EXISTS (SELECT Recovery_count FROM Tabella_nomi) = 0) THEN
INSERT INTO (Patients_table (Recovery_count)
ELSE
SET Recovery_count = select Recovery_count+1 from Patients_table
END
this seems wrong on many levels and MySQL useless syntax checker does not help.
How can I do this? Thanks.
There seems to be a lot wrong with this block of code. (No offense intended!)
First, Procedures need to be wrapped with BEGIN and END:
CREATE PROCEDURE nameInsert(IN nome, IN data)
BEGIN
...[actually do stuff here]
END
Second, since your table is declared with all fields as NOT NULL, you must insert all fields with an INSERT statement (this includes the Recovery_Date column, and excludes the AUTO_INCREMENT column). You can add DEFAULT CURRENT_TIMESTAMP to the date column if you want it to be set automatically.
INSERT INTO Patients_table (Patient_name,Recovery_Date) values (nome,data)
Third, what exactly is your IF predicate doing?
EXISTS (SELECT Recovery_count FROM Tabella_nomi) = 0
If you want to check if a row exists, don't put the = 0 at the end. Also, Tabella_nomi isn't declared anywhere in that procedure. Also, your SELECT statement should have a WHERE clause, since I'm assuming you want to select a specific row (this is going to select a result set of all recovery_counts).
Fourth, the second INSERT statement seems a little messy. It should look more like the first INSERT, and keep the point I made above in mind.
INSERT INTO (Patients_table (Recovery_count)
Fifth, the ELSE statement
SET Recovery_count = select Recovery_count+1 from Patients_table
Has some problems too. SET is meant for setting variables, not values in rows. I'm not 100% sure what your intent is from this statement, but it looks like you meant to increment the Recovery_count column of a certain row if it already exists. In which case, you meant to do something like this:
UPDATE Patients_table SET Recovery_count = Recovery_count+1 WHERE <conditional predicate>
Where the conditional predicate is something like this:
Patients_name = nome
Try these things, and look at the errors it gives you when you try to execute the CREATE STATEMENT. I bet they're more useful then you think!
I need to do this: On inserted record I need to store Inserted item identity and selected item identity. (Example below)
I'm using after insert trigger (basically I copy one row from one table into another and do some more modifications.
I have a table parameter like this:
DECLARE #Tempequipment TABLE
(Equipment_Id int,
DefaultEquipment_Id INT)
Then I insert into table like this:
INSERT INTO dbo.tblEquipmentType
( Name, EquipmentType_Id)
SELECT name,(SELECT Equiment_Id FROM INSERTED)
FROM dbo.tblDefaultEquipmentType
This works fine!
What I need to do is: I need to insert into #TempEquipment EquipmentTypeId's that were just ineserted (can be more than one) and DefaultEquipmentTypeId's that were just copied.
I was thinking about doing something like:
INSERT INTO dbo.tblEquipmentType
( Name, EquipmentType_Id)
Output EquipmentTypeId, DefaultEquipmentTypeId into #TempEquipment
SELECT name,(SELECT Equipment_Id FROM INSERTED)
FROM dbo.tblDefaultEquipmentType
but of course this is not going to work, since it cannot get values from select statement, and not written correctly.
Any help is appreciated!
UPDATE:
I have an Item. Item can be built on different equipment. Equipment has types (foreign key. And equipmentType has attributes (foreignkey).
So this mean that we have four tables Item->Equipment->EquipmentType->EquipmentAttribute.
I need to store default EquipmentTypes and default EquipmentAtrributes for that type.
So I also got these replationship: Equipment->DefaultEquipmentType->DefaultEquipmentAttribute.
Now, When I insert new Item and select an equipment I want to copy defaults over to real tables (EquipmentType, EquipmentAttribute).
Is it clear at least a little?
Aside from how you're trying to do this (which isn't working), what specifically are you trying to do?
It may be that this can be resolved by changing / normalizing your paradigm, instead of some kind of exotic code. For example, it looks odd to have a customers table with an orderID field in it. Unless your customers only ever order one thing... I would have expected to see a customers table, an items table, and then an orders table that joined customers with items.
Hope that makes sense -- but anyway, if not, can you post your table structure, and maybe be a little more clear on what you know ahead of time (e.g., I imagine you know who your customers are, and what they ordered...before you do the insert...yes?)
For an INSERT statement you can only access the columns which are in the insert column list, so the solution is to rewrite the statement as a MERGE statement which can access all the columns including columns which are in the INSERT target table for instance IDENTITY columns.
In the demo I've used dbo.INSERTED to emulate the virtual table INSERTED from the trigger.
USE master
GO
IF DB_ID('MergeOutputExample') IS NOT NULL
DROP DATABASE MergeOutputExample
GO
CREATE DATABASE MergeOutputExample
GO
USE MergeOutputExample
GO
DECLARE #Tempequipment TABLE
(EquipmentId int,
DefaultEquipmentId INT,
ID int);
CREATE TABLE dbo.INSERTED
(
EquipmentTypeId int PRIMARY KEY
);
CREATE TABLE dbo.tblEquipmentType
(
ID int IDENTITY(1,1),
Name varchar(50),
EquipmentTypeId int PRIMARY KEY
);
CREATE TABLE dbo.tblDefaultEquipmentType
(
EquipmentTypeId int,
DefaultEquipmentTypeId int IDENTITY(1,1) PRIMARY KEY,
Name varchar(50)
);
INSERT dbo.inserted
(
EquipmentTypeId
)
VALUES (1);
INSERT dbo.tblDefaultEquipmentType
(
EquipmentTypeId,
Name
)
VALUES (
1,
'Hammer'
);
MERGE dbo.tblEquipmentType AS ET
USING (
SELECT DE.EquipmentTypeId,
DE.DefaultEquipmentTypeId,
DE.Name
FROM dbo.tblDefaultEquipmentType DE
INNER JOIN dbo.INSERTED I
ON DE.EquipmentTypeId = I.EquipmentTypeId
) AS DET
ON ET.EquipmentTypeId = DET.EquipmentTypeId
WHEN NOT MATCHED BY TARGET
THEN INSERT
(
Name,
EquipmentTypeID
)
VALUES
(
DET.Name,
DET.EquipmentTypeID
)
OUTPUT DET.EquipmentTypeId,
DET.DefaultEquipmentTypeId,
INSERTED.ID
INTO #Tempequipment;
SELECT *
FROM #Tempequipment;
SELECT *
FROM dbo.tblEquipmentType;