SQL Statement Filtering Condition, What about Database Query Statement Condition Filtering?

To filter the email questions to please add to see who adds the most ??

Is your purpose to find out which mail records contain messages?

In your example, it's a record that can filter out the characteristics of most rows of emails, but you seem to have a problem with your thinking: the basic format of the email is name@enterprise. Category.

1.The message is definitely @;

2.The e-mail address is also definitely included. Target;

3.Symbol. Definitely behind the @;

Therefore, take @ in. The previous way will be more correct and more realistic than the way you enumerate.

select mail from member where (mail <>'') and (mail like '%@%') and (mail like '%.%') and (mail like '%gmail%' or mail like '%yahoo%' or mail like '%163%' or mail like '%126%' or mail like '%sina%' or mail like '%sohu%' or mail like '%21cn%' or mail like '%eyou%' or mail like '%263%' or mail like '%tom%' or mail like '%china%' or mail like '%188%' or mail like '%msn%' or mail like '%hotmail%' or mail like '%qq%' or mail like '%sogou%' or mail like '%qianlong%' or mail like '%alibaba%' or mail like '%eastday%' or mail like '%hexun%' or mail like '%everyone%' or mail like '%peoplemail%')

Oh, this question is so interesting, I thought that the mail is punctuated, so there is also ". ."There's also the length limit issue in front of @, and ......I don't know, you've written it all perfectly, hehe, it's just passing by.

create table tzqdm

id int identity(1,1) primary key,zqdm varchar(10),jys varchar(20)

insert into tzqdm(zqdm,jys) values('Zhang San','522125198704151513')

insert into tzqdm(zqdm,jys) values('Zhang San','245861198809101101')

insert into tzqdm(zqdm,jys) values('Zhang Shan','546854199901021111')

insert into tzqdm(zqdm,jys) values('Li Si','123987198012300101')

insert into tzqdm(zqdm,jys) values('Li Si','987654198012312121')

insert into tzqdm(zqdm,jys) values('Wang V','444254198711152020')

Let's say zqdm is the name.

JYS is an ID card.

The meaning of this SQL statement is to query two or more names with the same name but different ID cards.

select from tzqdm a,tzqdm b where and != group by

select * from [table name].

where Condition 1 and Condition 2 and Column is not null

If there is a question with the answer upstairs, these conditions should be separated into a separate filter condition in parentheses, otherwise, the results will not be accurately filtered by multiple fields.

For example, if B has a large and indefinite number of like items, C has two fuzzy matches, and there are other items, it should be written like this:

where 1=1 and (b like '% condition 1%.' or b like '% condition 2%.' ..

and (c like '% condition c1%.' or c like '% condition c2%.')

and ..

** Below:

select * form database name where field name not like'p%'and field name like'%-%'

If you have sql 2000 or more, use regular rules.

It should be select * from the table name where regexp instr(column name,'[a-z]')=0

select * from t a

where not exists(select * from t where course=.'a'and name=a.Name).

select * from t

where Name not in(

select name from t where course='a')

In this statement is the connection condition. If you use inner join in this way, you can only write query conditions to where before the table is written to on. If you write where in the above way, you can follow the link condition or add the filter condition.

This is a table join condition, there is no filter yet.

1. Statement: select * from where prod name='king doll' and prod_price>8。

Search for all columns in the table, and filter to all products manufactured by King Doll greater than 8.

Note: The character after --is the comment of this statement, this statement has two conditions, each joined by the and keyword, and the filter result must meet these two conditions, if only one of them is met, the data will not be retrieved.

2. OR operator (or).

Statement: select * from where prod name='king doll' or prod_price>8。

Search all columns in the table, and filter to all product values greater than 8 made by King Doll.

Note: -- The difference between the OR operator and the AND operator is that as long as one of the conditions is met, the value will be retrieved, for example, the data will be retrieved as long as one of the conditions is met.

3. In operator (specify the range of conditions).

Statement: select * from where prod name in ('king doll' ,'queen dool')。

Search for all columns in the table, filtered for products manufactured by King Doll and Queen Dool.

Note: It functions the same as OR, but it is faster and more concise, and the biggest advantage is that it can contain other select statements, and can create where statements more dynamically.