-1
votes
0answers
30 views

select data for field value ( where value is some int) if data is null select data for field value as Null [closed]

here i have a query which returns price for respective condition... what i am doing now... here i am haveing conditon where i am checking event_id is NULL or event_id = "some value" ... what i think ...
1
vote
1answer
28 views

cant order NULL value properly (mysql)

So I got this view in mysql : CREATE VIEW vote_question_totals AS SELECT question_id , SUM((vote_question_type)='1') question_total_plus , SUM((vote_question_type)='-1') question_total_minus , ...
0
votes
0answers
16 views

Avoid obvious potential NULL-values [duplicate]

I've been searching through the different threads discussing NULL values and how it is good whether using it or not. I cant find any concrete examples of how to design a relational data model to avoid ...
0
votes
1answer
210 views

MySQL warnings while loading integer data into table (SOLVED)

For some reason, after loading a large amount of data into the following table (from a single file), all of the values register as 0. CREATE TABLE secondTable ( freq int NULL, w1 int NULL, w2 int ...
0
votes
0answers
37 views

MySQL - query join returning zero recs from table with data

I've provided a file that has the table structure and some sample data that I'm working with. I don't understand why I'm getting nulls from a joined table, where there is data. Here's my query ...
1
vote
4answers
403 views

MySql Order by isnull() Performance Problem

my sql below is use for listing stock added from 10 days ago. Order by isnull(Price) is use so that stock without any price yet will still being listed. AddDate and Price has an index. SELECT Id, ...
0
votes
2answers
165 views

Two nullable columns one required to have value

No-Explanation Question: Is there anyway to have a constrain of 2 null values that always requires 1 to have value ? For example two date columns both null but having at least 1 that requires to have ...
0
votes
1answer
156 views

Creating a partial unique constraint for MySQL

I have the same question as asked in a previous post: PostgreSQL multi-column unique constraint and NULL values. But the solution there is not applicable as I am using MySQL instead of PostgreSQL. My ...
0
votes
1answer
2k views

WITH ROLLUP WHERE x IS NULL

I tried to find this question somewhere else on here, and found a couple that were similar to it -- but all the answers seemed pretty convoluted, and I think it was surprising to me because I just ...
3
votes
1answer
437 views

A function to check if a column allows NULL

Is there a way to write an insert/update query that checks if a column allows NULLs: If it does set the column to NULL, and '' (empty string) otherwise? I would be something like: UPDATE mytable ...
3
votes
2answers
11k views

Select column names whose entries are not null

I would like to have a list of those columns of a table that have at least one not-NULL data entries in them. In other words, I would like to get the column names for which the following returns at ...
3
votes
3answers
1k views

Empty LONGTEXT or NULL?

In my MySQL DB I have one field called html_contents that contains all the html to be shown in a webpage. Obviously the html could be huge, and certaintly bigger than 64KB, therefore I decided to use ...
1
vote
1answer
607 views

How to change the display of an empty string in mysql command line tool?

I'm maintaining a database with InnoDB tables. These tables have some columns of type (from show create table): `val0` varchar(30) default NULL, `val1` varchar(30) default NULL, etc... From the ...
1
vote
2answers
361 views

MYSQL only Show columns which allow null

I need to be able to pull the column names which allow a NULL value, I know that show columns from TABLE Will give show me the table properties and whether or not the column allows null values, ...
2
votes
1answer
874 views

Are many NULL columns harmful in mysql InnoDB?

As I explored the clustered B-tree index system of InnoDB, I think that the presence of many NULL (or small) columns has no significant effect on InnoDB performance. Does the presence of excess ...
4
votes
1answer
6k views

MySQL column defined with NOT NULL is allowing nulls

I had created a table a while back and started adding data to it. Recently I added a new column (address) to it with NOT NULL as part of the new column. The old rows (pre-addition) are still null, ...
2
votes
1answer
2k views

MySQL - LOAD DATA INFILE - Handling unescaped NULL in INFILE or creating INFILE with escaped NULL

I am selecting data from a database on server A, dumping the output into a file locally, and then doing a LOAD DATA INFILE on my local database. The bash command looks something like this: mysql -e ...
29
votes
2answers
6k views

NULL or NOT NULL by default?

In MySQL, is it better to always allow nulls unless you know a field is required, or always use Not Null unless you know a field will contain nulls? Or doesn't it matter? I know in some DBMSs they ...