what null

Town Yard text:The Confucian School of the practical and practical, line Buddhism Purdue sentient beings, the monastic Kangsheng fidelity, understanding of the easy to change the image. To science and technology to shine a good law, the achievement

Null indicates an unknown state and future state. For example, I don't know how much money James has in his pocket, but it cannot be zero, in this case, Null is used in the computer to indicate unknown and uncertain.Although those who are familiar

We all know that the value type cannot be null, but in some cases, the value type needs to be set to null. Therefore, CLR references the usage of the null type. Today'sArticleWhich of the following symbol estimates is? Now. ? -- First

Although the person who is proficient in SQL will not have any questions about NULL, but the whole article is still very difficult to find, see an English version, feel good.Tony Hoare invented the null reference in 1965 and considered it a

In the page often encountered control judgment, the textbox to take the value is empty, with "", in the database to obtain whether the data is null, for example two:1.function Trater (value,row,index) {if (value = null) {var len = row.

In sqlserver 2000, the null value of datetime is the default value 00:00:00. in C #, the null value of datetime is the minimum value 0001-01-01 00:00:00. For database insertion, the date value updated to a null value is somewhat less than expected.

I encountered a strange problem in a project, and it took me a lot of time to solve it. The final debugging found that it was a judgment problem-about 0 and ''(null single quotes, for better understanding, I added a space), I found that 0 = "was

Difference between NULL and MySQL NULL strings bitsCN.com Difference between NULL and MySQL NULL strings We often see MySQL NULL strings and NULL values, but they are not a concept. The following describes the differences between NULL and MySQL

In the Access Project (that is, the. ADP file) linked to an SQL Server database, the access function that you frequently use is usually not supported. But most of the time, you can use a Transact-SQL (T-SQL) function supported by SQL Server. One

The concept of null values is a common cause of confusion among novice sql, who often assume that null is the same thing as an empty string. That's not true! For example, the following statements are completely different: Mysql> INSERT into

An order by ordering in MySQL encountered a problem with a null value MySQL database, when order by ordering, if there is a null value, then NULL is the smallest, ASC is ordered, the null value is at the front. What if we want NULL to be followed by

"" Memory allocated; null When a null string is called, a null pointer is thrown. "" Is a string. It exists in the memory. It can use methods in the object (such as "". tostring (); "". Equals ()) Null is an empty object. It does not exist in the

Not NULL | Null: Specifies whether the column is allowed to be empty. If neither NULL nor NULL is specified, the column is considered to have null specified In MySQL, Set a null value for a NOT null field, It's not going to go wrong, MySQL

The MySQL database is an open source database based on structured data. The SQL statement is the core language in the MySQL database. However, in the MySQL database to execute SQL statements, you need to be careful two traps. Trap one: null value

The MySQL database is an open source database based on structured data. The SQL statement is the core language in the MySQL database. However, there are two pitfalls to take care of when executing SQL statements in a MySQL database.Trap one: null

Occasionally, I saw this problem in a blog. At that time, the author cited a lot of ecmascript specifications, which are still in English, and I was dizzy. Now I will put the conclusions of others here. If you have time, write this blog according to

In java, after the String type string s is assigned null, the String is spliced with other strings to obtain the style of the null string connected to other characters. The String value is null. String s = null; S + = "hello "; System. out.

Several methods for judging null variables in PHP are shared. 1. isset: determines whether a variable is initialized. description: it does not determine whether the variable is null and can be used to determine whether the elements in the array are

"Ambiguity analysis of Null values"When it comes to null values, a lot of people are familiar with it, but after a deep understanding, they feel unfamiliar, and their meaning and usage can not be accurately understood. Null in databases and

NULL in the computer and programming world represents an unknown, indeterminate. Although the Chinese translation is "empty", this empty (null) is not Pethin (empty). Null represents an unknown state, the future state, such as how much money in Xiao