Lowest common denominator max URL length among popular web browsers: 2,083 (Internet Explorer) http://dev.mysql.com/doc/refman/5.0/en/char.html Values in VARCHAR columns are variable-length strings. The length can be specified as a value from 0 to 255 before MySQL 5.0.3, and 0 to 65,535 in 5.0.3 and later versions. The effective maximum length of a VARCHAR in MySQL 5.0.3 … Read more
In addition to violating First Normal Form because of the repeating group of values stored in a single column, comma-separated lists have a lot of other more practical problems: Can’t ensure that each value is the right data type: no way to prevent 1,2,3,banana,5 Can’t use foreign key constraints to link values to a lookup … Read more
I’m in charge of some applications that manage many TB of images. We’ve found that storing file paths in the database to be best. There are a couple of issues: database storage is usually more expensive than file system storage you can super-accelerate file system access with standard off the shelf products for example, many … Read more
psql -U username -d mydatabase -c ‘SELECT * FROM mytable’ If you’re new to postgresql and unfamiliar with using the command line tool psql then there is some confusing behaviour you should be aware of when you’ve entered an interactive session. For example, initiate an interactive session: psql -U username mydatabase mydatabase=# At this point … Read more
See the docs FAQ: “How can I see the raw SQL queries Django is running?” django.db.connection.queries contains a list of the SQL queries: from django.db import connection print(connection.queries) Querysets also have a query attribute containing the query to be executed: print(MyModel.objects.filter(name=”my name”).query) Note that the output of the query is not valid SQL, because: “Django … Read more
Laravel 4: Change “host” in the app/config/database.php file from “localhost” to “127.0.0.1” Laravel 5+: Change “DB_HOST” in the .env file from “localhost” to “127.0.0.1” I had the exact same problem. None of the above solutions worked for me. I solved the problem by changing the “host” in the /app/config/database.php file from “localhost” to “127.0.0.1”. Not … Read more
Try this: If your collection was ‘example’ db.example.update({}, {$unset: {words:1}}, false, true); Refer this: http://www.mongodb.org/display/DOCS/Updating#Updating-%24unset UPDATE: The above link no longer covers ‘$unset’ing. Be sure to add {multi: true} if you want to remove this field from all of the documents in the collection; otherwise, it will only remove it from the first document it … Read more
Several people misread this as a question about how to store passwords in a database. That is wrong. It is about how to store the password that lets you get to the database. The usual solution is to move the password out of source-code into a configuration file. Then leave administration and securing that configuration … Read more
For formatted output: describe [db_name.]table_name; For an SQL statement that can be used to create a table: show create table [db_name.]table_name;
Lone Ranger is very close… in fact, you also need to specify the datatype of the renamed column. For example: ALTER TABLE `xyz` CHANGE `manufacurerid` `manufacturerid` INT; Remember : Replace INT with whatever your column data type is (REQUIRED) Tilde/ Backtick (`) is optional