I have a table with more than 1 million records, in 2 columns with datatype varchar(50) I have values like 23.23.
I need to convert the data/values to int.
For Example, 23.23 to 23 by remove the floating points.
I don't have primary key on this table.
ALTER TABLE t1 CHANGE <column_name> <column_name> <type>
note: you have to write column name twice
OR
ALTER TABLE t1 MODIFY <column_name> <type> ;
Reference
You can use FLOOR:
SELECT FLOOR(columnName)
FROM TableName
Floor returns the largest integer value not greater than X.
Read more here.
To convert the datatype of the field:
ALTER TABLE TableName CHANGE columnName newColumnName targetFieldType;
Try this:
SELECT ROUND(5.693893);
SELECT FLOOR(7.55);
You can try casting this field to a Decimal.
SELECT CAST(field AS DECIMAL(10,0)) FROM table;
I had the same issue. My table has a field that is of type 'float' which I needed to be of type 'int'.
Thanks to Neels!
So, I had to first convert the field to be of type DECIMAL with 10,0 (no value after decimal) and then convert the field to be INT with length 11 for example.
ALTER TABLE track CHANGE type type DECIMAL(10,0);
ALTER TABLE track CHANGE type type INT(11);
ALTER TABLE tablename CHANGE columnname columnname INT
Related
I need to change column type from tinyInt(used as bool) to Varchar, without loosing data.
I have found many answers on stack-overflow but all of them are written in postgres and I have no idea how to rewrite it in Mysql.
Answers for this problem on stack-overflow looks like that:
ALTER TABLE mytabe ALTER mycolumn TYPE VARCHAR(10) USING CASE WHEN mycolumn=0 THEN 'Something' ELSE 'TEST' END;
How would similar logic look like in Mysql?
The syntax you show has no equivalent in MySQL. There's no way to modify values during an ALTER TABLE. An ALTER TABLE in MySQL will only translate values using builtin type casting. That is, an integer will be translated to the string format of that integer value, just it would in a string expression.
For MySQL, here's what you have to do:
Add a new column:
ALTER TABLE mytable ADD COLUMN type2 VARCHAR(10);
Backfill that column:
UPDATE mytable SET type2 = CASE `type` WHEN 0 THEN 'Something' ELSE 'TEST' END;
If the table has millions of rows, you may have to do this in batches.
Drop the old column and optionally rename the new column to the name of the old one:
ALTER TABLE mytable DROP COLUMN `type`, RENAME COLUMN type2 to `type`;
Another approach would be to change the column, allowing integers to convert to the string format of the integer values. Then update the strings as you want.
ALTER TABLE mytable MODIFY COLUMN `type` VARCHAR(10);
UPDATE mytable SET `type` = CASE `type` WHEN '0' THEN 'Something' ELSE 'TEST' END;
Either way, be sure to test this first on another table before trying it on your real table.
The code is
Select location,date, total_cases,total_deaths,
(total_cases/total_death)*100 as death percentage
Both total_cases and total_death contain varchar
How do I cast or convert them
You can solve the problem like this :
Select location,date, total_cases,total_deaths,
(CAST(total_cases as SIGNED)/CAST(total_deaths as SIGNED))*100 as death_percentage
from tab ;
it is more practical to modify the types of the two columns like this :
ALter table tab modify total_cases integer ;
ALter table tab modify total_deaths integer ;
I have a database with a column named "price" - within this column there are prices rounded to 5 decimal places, e.g 62.083333 - I would like to run a command to change every value within "price" column to just 2 decimal places, e.g 62.08
Is there a simple command to run on this column? We have over 36,000,000 values so would prefer not to have to update them all manually! :)
Would this command be the one?
SELECT CONVERT(DECIMAL(20,2),price)
Here's a similar question: mass update mysql table decimal value and change column field type
You can use
ALTER TABLE '<name>' CHANGE COLUMN '<name>' DECIMAL(20,2)
Simply alter table and modify data type
ALTER TABLE [TableName] MODIFY COLUMN [ColumnNameHere] decimal(20,2)
Try ,
UPDATE table_name SET price = round(price,2) where your
conditions;
I stored date as a
varchar(256) latin1_swedish_ci
which shows up as: 11/22/2012
Now I wanted to convert the existing data and column to a DATE
What would be the easiest way to do this in SQL
thanks
To be on the safe side I personally would add a new column, Transfer the data and then delete
update `table` set `new_col` = str_to_date( `old_col`, '%m/%d/%Y' ) ;
Check the data is OK before you delete the column.
Edit to convert the existing data use:
STR_TO_DATE(t.datestring, '%d/%m/%Y')
Source: Convert String to Date
You may need to create a temp table to hold your data for conversion:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
(create_definition,...)
[table_options]
[partition_options]
Then you can truncate the table:
TRUNCATE [TABLE] tbl_name
Then you can alter the column datatype:
ALTER TABLE tablename MODIFY columnname DATE;
Then you can reload from the temp table:
INSERT INTO table
SELECT temptable.column1, temptable.column2 ... temptable.columnN
FROM temptable;
Use the STR_TO_DATE function.
Make a new column that is the correct datatype, move the strings from the old column into the new one with the STR_TO_DATE function, and then delete the old column.
UPDATE table SET new_col = STR_TO_DATE(old_col);
MySQL STR_TO_DATE Reference.
I need to add a "0" before a integer field in a MYSQL table. How do I update those fields so they have a ) added to them? Thanks.
You can't unless you change the column type to string. However you can add the zero when reading the field:
SELECT CONCAT( '0', int_col ) FROM ....
If you want to format the output of all integer values in one column to a fixed column size, say 5, with leading zeroes for small numbers, use an ALTER TABLE statement like:
ALTER TABLE table MODIFY `col` INT(5) ZEROFILL;
Refer to MySQL 5.1 Reference Manual.