mysql change date format - mysql

I have a date field (tinytext) holding date information in format of "dd-mm-yy" e.g 07-01-90. Using a mysql query I want to change it to yyyy-mm-dd date format. I tried the code below but nothing happens.
mysql_query("UPDATE Table SET date=STR_TO_DATE('date','%Y,%m,%d')");

You're using the correct function STR_TO_DATE(str,format) to achieve the goal, but you're making two mistakes:
In your query the format argument does not match the string expression format. You said it's in dd-mm-yy format while you passed %Y,%m,%d (comma separated) to the format argument. The query will return a "incorrect datetime value" error. You should use %d-%m-%Y.
You can't change data type of a column on the fly, by setting different type of the value being passed. You have to first update the values and then change data type for column.
So, summarizing:
mysql_query("UPDATE `Table` SET `date` = STR_TO_DATE(`date`, '%d-%m-%Y')");
mysql_query("ALTER TABLE `Table` CHANGE COLUMN `date` `date` DATE");
Additionally, consider switching to the recommended PDO extension in place of old and slowly deprecated mysql extension.

Error in your query
is STR_TO_DATE(date, '%Y-%m-%d')
mysql_query("UPDATE Table SET date=STR_TO_DATE(date,'%Y-%m-%d')");

Try this:
INSERT INTO table(date_field) VALUES(STR_TO_DATE('December 8, 2010','%M %d,%Y'));

Try it with DATE_FORMAT() function.
mysql_query("UPDATE Table SET date=DATE_FORMAT(date,'%Y,%m,%d')");

To display 2 digit year
mysql_query("UPDATE Table SET date=DATE_FORMAT(date,'%y-%m-%d')");
To display 4 digit year
mysql_query("UPDATE Table SET date=DATE_FORMAT(date,'%Y-%m-%d')");

I'd say you have to do this:
UPDATE table_name SET date = DATE_FORMAT('date', %Y-%m-%d);

If you are using my_sql with php, you can use date function

Related

MySQL: How to set a DATE column by converting all values in a VARCHAR column?

I have a table in which there is a column called "DATE" which contains dates in the format "23-Nov-2017" as datatype VARCHAR. I'm trying to convert this VARCHAR column and store it in a new column called "NEWDATE" of datatype DATE.
I have created the new column "NEWDATE" of type DATE and I am trying to use the STR_TO_DATE() function to perform the conversion. However, I can't get it to work for some reason.
UPDATE table SET NEWDATE = STR_TO_DATE(DATE,'%d-%m-%Y');
The NEWDATE column is not updated with any values after the statement. I guess this means that the statement does not execute. What am I doing wrong?
EDIT: I have also tried STR_TO_DATE(DATE,'%d-%b-%Y'). However there is still no change to the values in the NEWDATE column
Your format '%d-%m-%Y' does not match your actual date string "23-Nov-2017"
The %m is for numeric month and you have an abbreviated text month
Use %b for 3 char month values like this:
STR_TO_DATE(DATE,'%d-%b-%Y')
EDIT: WorkBench issue
That is just a Workbench config setting to stop you accidentally issuing a HUGE update. You can either turn that setting OFF or frig it a bit by giving it a WHERE clause that will allow it to run like below. Below assumes this table has an id column
UPDATE table SET NEWDATE = STR_TO_DATE(DATE,'%d-%b-%Y') WHERE id<10000000;
Or
UPDATE table SET NEWDATE = STR_TO_DATE(DATE,'%d-%b-%Y') WHERE id>0;

Alter Query To Change Date Format

How can i use the alter query to change a DATE format in mysql
for example
ALTER table userdata ADD column DateofBirth DATE SET = '%d-%m-%Y';
I tried this and it didnt work.
If your dates are stored in column with type DATE. You can set date format in SELECT query:
SELECT DATE_FORMAT(DateofBirth ,'%d-%m-%Y') AS DateofBirth FROM userdata;
There is no "date format" specified with the DATE datatype. It's not possible to specify a format with the column definition.
MySQL does provide a couple of useful functions... STR_TO_DATE and DATE_FORMAT that convert between DATE and string representations, in a variety of formats.
Reference: http://dev.mysql.com/doc/refman/5.7/en/date-and-time-functions.html#function_date-format
If am not wrong, you need a update statement
Update userdata set DateofBirth = DATE_FORMAT(DateofBirth ,'%d-%m-%Y')
But it is better to store dates in DATE datatype

Converting String Data Value into date

Good Morning All;
I currently have a MySQL table where there are 3 date fields (Columns) that were loaded as strings in this format 20140101 YYYYmmdd. I would like to convert this to a date format 2014/01/01 YYYY/mm/dd. Can someone please provide a simple sql syntax that would alter the table to a date format from a string and change the column to display the dates like this 2014/01/01 and not like 20140101. Thanks to all
Try this:
date_format(str_to_date(datecolumn, '%Y%m%d'),'%Y/%m/%d')
If you just want to reformat the values in the VARCHAR column, assuming that the column with sufficient length e.g. VARCHAR(10), and all the values are eight characters in length...
You could do something like this:
UPDATE mytable t
SET t.mycol = CONCAT( LEFT( t.mycol ,4)
, '/'
, SUBSTR( t.mycol ,5,2)
,'/'
, SUBSTR( t.mycol ,7,2)
)
WHERE CHAR_LENGTH(t.mycol) = 8
We want something in the statement that will prevent the statement from "working" a second time, if it's inadvertently re-run. It doesn't have to be CHAR_LENGTH. We might want to include a check that the value doesn't already contain a slash character AND t.mycol NOT LIKE '%/%'.
But why on earth are "date" values being stored in character columns, rather than in DATE datatype, which is custom designed for storing and working with date values?
ALTER TABLE mytable MODIFY mycol DATE ... ;
(If the column is defined as NOT NULL, has a default value, has a comment, those attributes can be retained, they need to be included in the new column specification, e.g.
ALTER TABLE mytable MODIFY mycol DATE NOT NULL COMMENT 'creation date';
Note that DATE columns do not have a "format" per se. When converting to string, MySQL uses date format '%Y-%m-%d'. And MySQL expects string literals representing date values to be in that same format. To get a value from a DATE column converted to string in format 'yyyy/mm/dd'.
SELECT DATE_FORMAT(date_col,'%Y/%m/%d') AS date_col
To get a string value in that format converted to DATE datatype
SELECT STR_TO_DATE('2015/06/01','%Y/%m/%d')

Convert varchar column to date in mysql at database level

I have one column date1 which is varchar type
I want this column to date type.
I tried changing field but all date is converted to 0000-00-00.
format is dd-mm-yyyy but in varchar.
How can I convert the same date format but with date format using sql queries or similar but at database level ?
UPDATE `table`
SET `column` = str_to_date( `column`, '%d-%m-%Y' );
More about STR_TO_DATE function.
Since your column name is date1, you can replace column with date1 in the above syntax, and the code shall be:
UPDATE `table`
SET `date1` = str_to_date( `date1`, '%d-%m-%Y' );
The other answers here are risky, because if they go wrong you'll lose your data. A safer way to do this is to create a new field on your database with a DATE (or DATETIME if you need time as well) format, then to run a query like
UPDATE `table` SET `my_new_date_field` = STR_TO_DATE( `my_old_data_field`, '%d/%m/%Y');
In this way, if the %d/%m/%Y bit is wrong, you won't lose your data.
Once you're happy, you can delete the old data field and rename the new one.
use STR_TO_DATE Function of MySQL
FIRST you will need to update the value in date format.
UPDATE `tbl` SET `date1` = STR_TO_DATE(`date1`, '%d-%m-%Y') WHERE 1=1
THEN Convert the field to date.
Most importantly remember to insert date as Y-m-d format, after then.

How to convert a varchar column type to date type without losing the dates

I am looking for a way to change the datatype of a column. Currently, in my database, the date columns types were defined as varchar and I need to convert them back to the date type.
Any idea how to do it?
You will need to adapt this based your your exact table structure but something like;
CREATE TABLE temp (startdate varchar(255), stuff varchar(255));
INSERT INTO temp
SELECT startdate,stuff
FROM mytable;
TRUNCATE TABLE mytable;
ALTER TABLE mytable ALTER COLUMN startdate DATETIME NOT NULL;
INSERT INTO mytable
SELECT CAST(startdate AS DATETIME), stuff FROM temp;
DROP TABLE temp;
First, create the new column with type data
Next, run update query, to populate the new column with the value of the old one, applying any conversion if needed
Next, drop the old column
Finally, rename the new column to the old one
Create a new DATE column with a temporary name
Populate the new column with an UPDATE query that makes use of STR_TO_DATE()
If everything's right, remove the VARCHAR column and rename the DATE column.
Mysql default date format is : YYYY-MM-DD . If your try to insert the date otherwise, as you actually did, the date will be inserted with these values : 000-00-00, giving you a hint to the acceptable date format for mySql.
Wanna share this for SQL server users. For me this method is much convenient and safer.
In your Table create new column "NewDate" (temporarily or name whatever you want).
Make sure no invalid Datetime format in the Table you want to convert. Try those formats here: https://www.w3schools.com/sql/trysqlserver.asp?filename=trysql_func_sqlserver_cast3 <--- you need to check thoroughly otherwise there would be an error executing the command below.
Execute this command:
UPDATE myTable
SET NewDate = CAST(OldDate AS datetime)
WHERE (OldDate <> '') AND (OldDate IS NOT NULL) --to make sure you cast only what is needed otherwise there would be an error.
You can now delete the old column i.e. "OldDate".
Finally you can drag and drop the new table you've created to the slot where you just deleted the old column in the table design.
If the field of your column is VARCHAR and stored date as DD-MM-YYYY then we have to convert the date in YYYY-MM-DD format by following PHP code.
$cd = array();
$cd1 = array();
$cdf = array();
$getdata = mysqli_query($link,"SELECT columnname FROM tablename");
while($row=mysqli_fetch_array($getdata))
{
$cd = $row['columnname'];
$cd1 = strtotime($cd);
$cdf = date('Y-m-d',$cd1);
mysqli_query($link,"UPDATE tablename SET columnname =
REPLACE(columnname,'$cd','$cdf')");
}
After running this PHP code, in your MySQL table change the datatype of your column to 'DATE'.
It works for me without losing or truncate data.