if then clause

1.where cannot be placed behind group by2.HAVING is used in conjunction with group by, placed behind group by, at this time the role is equivalent to where3.WHERE The following conditions cannot have aggregation functions, such as SUM (), AVG (),

Differences in the WHERE clause and the HAVING clause in Oracle1.where cannot be placed behind group by 2. Having is used together with group by, placed behind group by, at this time the function is equivalent to the where3.where behind the

1.where cannot be placed behind group by 2. Having is used together with group by, placed behind group by, at this time the function is equivalent to the where3.where behind the condition can not have aggregation function, such as SUM (), AVG (),

Clause 10: Make operator= return a reference to *thisHas assignment operators return a reference to *thisWith regard to assignments, they can be written in a chain form:int x, y, z;x = y = z = 15; The assignment uses the right binding law, so

Detailed explanation of the usage of the sentence clause (rich examples)   I. Guiding Words of sentence clauses The words that guide the sentence clauses usually have the words that, whether, the connected pronoun and the connected adverbs. 1.

Article 36 Never redefine inherited non-virtual functions Article 37 Never redefine inherited default parameter values Article 36: Never redefine inherited non-virtual functionsUse an example to expand the content of the article. Assume

Software design is the "Let the software do what you want it to do" steps and practices. Start with a general idea, gradually clear, structure the details, and finally design a good interface (interface). These interfaces then become declarations of

Today, I came into contact with the group by clause with the rollup clause (it's really ugly. I 've been in contact with ORACLE for a year or two before I know this usage ), the functions produced by the group by clause with the rollup clause are

Clause 46 When you enter conversions, you need to define non-template member functions Clause 47 Please use the Traits class expression type information Clause 46: Defining a non-member function for a template when a type conversion is

Clause 26 to postpone the occurrence of variable definitions as long as possible Clause 27 try to do less transformational action Clause 26: Delay the occurrence of variable definitions whenever possibleDefine a variable in the