#is null

A NULL value is a field with no value.It is very important to understand that the value of NULL is different from the zero value or a field containing spaces.   Syntax For Creating NULL Table CREATE TABLE Students( ID INT NOT NULL, NAME VARCHAR (225) NOT NULL, GENDER VARCHAR (225) , ADDRESS VARCHAR (225) , PRIMARY KEY (ID) ); Here, NOT NULL means that the column must accept the specified value of…

The regular SQL is null update query  may fail while updating Access database. Access DB has some different is null checking system. Put the Is Null statement at the end of the where section may fix the problem.

Here is the query

UPDATE Sales SET Sales.Taxable = 0 WHERE Sales.Taxable Is Null

Replace values from other columns if value of one column is null using awk/sed

I am trying to modify a tab delimited file by replacing the value of 2 columns separated by “:” where there is a null value in one column:

Start with this file:

id1 id2 pos1 pos2 749 2847443 21 13517135 862 2821796 21 13571669 997 21 13636494 1095 2821826 21 13661335 1131 21 13678797

I would like to modify column 2 to get this:

id1 id2 pos1 pos2 749 2847443 21 13517135…

MySQL のNULL ではまったことあれこれ – Slow Dance.

MySQLでのSQLで

ある項目が　NULL のもの出したいのに・・・

SELECT * FROM SAMPLE WHERE ID = NULL

とか　書いても何も出ない・・・

じゃあアレか！と思って

SELECT * FROM SAMPLE WHERE ID = ”

あれ・・・これもダメか・・・ 空文字とNULLの意味は違うんですよ。　・・・知ってるよ！！( ｀д´) ｹｯ!

結果的には NULL　かどうかを調べるには　IS NULL って書けや！　って話なんさ。

なんでもいっつも忘れるんだろうか・・・

要するに！！

　SELECT * FROM SAMPLE WHERE ID IS NULL

ってことでしたーーー！

知ってるよ・・・( ｀д´) ｹｯ!

ちょっぴり自己嫌悪（笑）