types of certifications

Varchar Variable-length non-Unicode data, which can contain a maximum of 8,000 characters. String Text Variable-length non-Unicode data. The maximum length is 2 ^ 31-1 (2,147,483,647) characters. String Unicode string Nchar Unicode data of a fixed length. The maximum length is 4,000 characters. String Nvarchar A variable-length Unico

Sometimes, you may face the issue of not knowing how many variables there will be in the data in the future, and write all the variables at once, or when you are faced with variables, it is obviously not a good method to constantly modify the class source code to expand new data records. at this time, you can use the index + binding method to solve the problem: the data of the class source code only has one uid (used for indexing) used to differentiate transactions, and new data needs to be exte

MyBatis through the contained Jdbctype types BIT FLOAT CHAR TIMESTAMP other UNDEFINEDTINYINT Real VARCHAR BINARY BLOB NVARCHARSMALLINT DOUBLE LongVarChar VARBINARY CLOB NCHARINTEGER NUMERIC DATE longvarbinary BOOLEAN NCLOBBIGINT DECIMAL Time NULL CURSOR Javatype and Jdbctype corresponding and crud examples in MyBatis XML code

We all know that the two data types of c # Are value type and reference type respectively. Many people may be able to tell with closed eyes that the value types include simple type, struct type, and enumeration type. The reference types include custom classes, arrays, interfaces, and delegation, however, when asked about the relationship and difference between th

C # Reference types and value typesThe CLR supports two types: reference types and value types.1. Reference types(1) The memory must be allocated from the managed heap;(2) Each object allocated on the heap has some additional members (including "type Object pointer", "Synchr

JAVA Learning (III): Basic Java syntax (conversion of variables, constants, data types, operators and data types), java OperatorsBasic Java syntax (conversion of variables, constants, data types, operators, and data types) 1. Variables In Java, you can declare variables by specifying data

JavaScript basic Data type:JS basic data types include: Undefined,null,number,boolean,string. The base data type is accessed by value, which means that we can manipulate the actual values that are saved in the variable.　　1. The value of the base data type is immutableNo method can change the value of a primitive type, such as a string:var name = "Change"; Name.substr ();//hangconsole.log (name);//changevar s = "Hello"; s.touppercase ()//hello; Console

Java Basic Data type wrapper class The Java language is an object-oriented language, but the basic data types in Java are not object-oriented, and this is a lot of inconvenience in the actual use, in order to solve this problem, in the design of the class for each basic data type design a corresponding class to represent, These eight classes corresponding to the basic data type are collectively referred to as the wrapper class (wrapper class), and so

The CLR supports two types: reference types and value types. Reference types are always allocated from the managed heap. The new operator in C # returns the memory address of the object. Note Points for referencing objects: 1. Memory allocated from the managed heap 2, the heap on the allocation of objects, there

the field types in the database correspond to the data types in C #:Database C # programsint int32Text stringbigint Int64Binary system.byte[]Bit BooleanChar stringDateTime System.DateTimeDecimal System.DecimalFloat System.DoubleImage system.byte[]Money System.DecimalNCHAR Stringntext StringNumeric System.Decimalnvarchar StringReal System.Singlesmalldatetime System.DateTimesmallint Int16SmallMoney System.Dec

1. Value type data in the stack, reference type data in the heap.2. Value types store the values of data directly, whereas reference types store references to data.3. Base class for value types: System.valuetype,system.valuetype is also inherited from System.Object. base class for reference type: System.Object.4. Value types