I wonder if there is some type of common method that would help me write query with date/time field in it. For example: I am developing a very small project utilizing MySQL database. However, my client is considering switching to his existing SQL server.
Example (datetime column):
SELECT DATE_FORMAT(contract_date, '%d.%m.%Y') FROM `employees`
Question: Can query below become usable in SQL in case I replace database driver (currently) mysqli to sqlsrv?
I understand I can use some type of config variable for date format... Would it be the best way? Is there something that Codeigniter 3 has in place?
feel free to use your own query sample
Related
I'm writing tests for my Laravel application and using MySQL for my development database but using SQLite in memory for my testing database with PHPUnit.
I'm trying to write a query that will get the current datetime for my development query and for the testing of my query.
Right now I have the following.
->select(DB::raw('DATEDIFF(IFNULL(DATE(champions.lost_on), now()), DATE(champions.won_on)) as length))
It says that I can't use now() with SQLite. Does anyone have a suggestion?
According to this answer you will need something like:
SELECT julianday(champions.won_on) - coalesce(julianday(champions.lost_on), julianday('now'))
You might want to cast that to integer.
Function Similar with to_char(datetime) that can be used both Oracle and MySQL?
I want to generate the ANSI SQL script to run both in oracle and in MySQL.
But, the generated ANSI SQL is working well. except the the error from to_char().
Is there any function that can be used in both db?
Date formatting abilities couldn't be more different. I think your best chance is to pick one of these:
Run an ALTER SESSION statement when you connect to Oracle to replicate the MySQL default date format and do all date formatting in your client app.
Write a custom wrapper function and use it in your queries. You have to fork function code and maintain two versions.
You still have DBMS-dependent code but it's isolated in your initialisation code (option #1) or your installation script (option #2).
Perhaps there's a third option: tweak your database abstraction library to detect column types in result sets and convert dates to custom objects (e.g., DateTime if you use PHP, Date if you use JavaScript, etc.).
Mysql and Oracle uses different syntax for converting date to string.
You should use different queries.
I am trying migrate a table from Vertica to Mysql.
I noticed that my table has a Vertica datatype interval.
The column details state that data sub type is Interval Day to Second
A sample data looks like 0 00:49:51.267000
I was wondering if there was a mysql equivalent, if not what could be the best possible match to store the data
There is no equivalent that I know of.
I would just store it in a varchar() by the looks of that character string.
However, if you want to investigate further and see what other data types are available to you here is a good place to start dev.mysql
You could use a TIME(6) type and load it with a VARCHAR version of the interval. You then would be able to do queries like:
SELECT TIME_TO_SEC(field) FROM TABLE;
SELECT MICROSECOND(field) FROM TABLE;
Just depends I guess on what you are trying to do with it.
My current application was built up in SQL Server 2008 server in JAVA with Hibernate and I had used HierarchyId data type for department hierarchy in my database.
I had written SQL queries to deal with HierarchyId datatype. And I also have n-Level of department tree structure.
Now I want to change my Database server from SQL Server 2008 to MySQL as per business requirement.
After feasibility checking I came with the solution that my whole application will migrate to MySQL database server except HierarchyId data type.
So my main challenge is to find alternate solution of HierarchyId data type with the minimal change in coding.
What is the best way to implement department hierarchy in my database?
Thanks...
I faced the similar situation when our team decided to migrate from MS-SQL to MySQL. We resolved the issue using the following steps:
Added a column of type varchar(100) to the same table in MS SQL.
Converted the hierarchyid from hexadecimal value to string using the hierarchyid.ToString() function as saved it in the newly created column using computed column functionality. for eg. 0x58 -> "/1/", 0x7CE0 -> "/3/7/".
The level of the entity is equal to no-of '/''s minus 1.
These columns could be migrated to the MySQL.
The IsDesendantOf() and is method was replaced with LIKE function of string concaenated with '%'.
Thus we got rid of the hierarchyid functionality in MySQL.
Whenever we face such an issue, we just need to ask ourselves, what would we have done if this functionality would not have been provided by the tool we use. We generally end up getting the answer optimally.
Mysql has no equivalent that I'm aware of, but you could store the same data in a varchar.
For operations involving the HierarchyId, you're probably going to have to implement them yourself, probably as either user defined functions or stored procedures.
What sqlserver does looks like the "materialized path" method of storing a hierarchy. One example of that in mysql can be seen at http://www.cloudconnected.fr/2009/05/26/trees-in-sql-an-approach-based-on-materialized-paths-and-normalization-for-mysql/
I'm trying to convert a postgresql sql-query to mysql. Using a translator.
this is the query in postgres:
comment_date_gmt timestamp without time zone DEFAULT timezone('gmt'::text, now()) NOT NULL,
it's converted to
comment_date_gmt timestamp DEFAULT timezone('gmt',
The none-closed parenthesis is a sign that everything isn't right. I'm trying to figure out what this query should look like. Any suggestions?
The only reliable SQL query dialect converter is the human brain.
Tools can be useful for the basics, like data type renaming, but lots of that sort of thing can be avoided by just writing the queries using standard types in the first place.
You'll have a very hard time converting a MySQL query that uses query variables to a PostgreSQL query, or converting a PostgreSQL (well, SQL-standard) recursive common table expression to something MySQL understands. The two have totally different stored procedure languages, different built-in functions, and all sorts of things. array_agg, unnest, etc ... most of that stuff would require translation to queries using MySQL variables where it's possible to do it at all. Then you've got window functions like row_number, lead, lag, and aggregates used as running windows like sum(blah) OVER (...). A generic converter would need to "understand" the query to actually do the job.
A specific answer for the named problem isn't really possible since you haven't identified the converter tool.
At a guess, if you change the PostgreSQL query to:
comment_date_gmt timestamp without time zone DEFAULT (current_timestamp AT TIME ZONE 'utc') NOT NULL,
which is the standard phrasing understood by PostgreSQL and other compliant databases.