types of database

Oracle's XML implementation?Oracle has implemented XML through the XML DB component of the database tutorial, which is the standard feature of the Enterprise and Standard editions. Oracle XML DB can be easily installed through the database Configuration Assistant (DBCA) or by running a directory script catqm.sql. The XML DB product provides all the features discussed in this article. To verify that the XML

quite a few. ODBCYes. NET Framework1.1New features can be used for other types of databasesODBC. Therefore, the above two connection methods are enhancedSPLMore powerful support for multiple databases. SPL3.0In the previous version2.0Is partially modified.BUGAnd added some new features. SPL3.0RevisedBUG: 1.PairOracleAn error is reported when the database compares dates.OracleThe da

In many applications, although the general use of a database operation, but due to the needs of various situations, the business system may be deployed in different types of databases, if the development of the system can easily support a variety of database switching, it can reduce the number of problems for us, while improving the adaptability and robustness of

MySql Type name Display Length Database Type JAVA type JDBC index (int) Description VARCHAR L + N VARCHAR Java. lang. String 12 CHAR N CHAR Java. lang. String 1 BLOB L + N BLOB Java. lang. byte [] -4 TEXT 65535 VARCHAR Java. lang. String -1 INTEGER 4

MySql connector JAVA type name display length Database Type JAVA type JDBC Type Index (int) Description VARCHARLNVARCHARjava. lang. String12CHARNCHARjava. lang. String1BLOBLNBLOBjava. lang. byte []-4TEXT65535VARCHARjava. lang. S MySql ----------------------------------- JAVA type name display length Database Type JAVA type JDBC Type Index (int) Description varchar ln varchar java. lang. string 12 char n cha

SQLite is especially convenient for storing mobile phone data, but I found some problems during usage: Data Type: Case Insensitive Text Text Numeric Value Integer Integer Real Decimal None No type The above data type is correct. 1. However, if you use other data types such as varchar to create a table, an error occurs. You cannot create a table. 2. If you have used some SQLite table creation tools to create tables, including v

Underlying data type Java type SQL type int or Java.lang.Integer INTEGER Long or Java.lang.Long BIGINT Short or Java.lang.Short SMALLINT float or java.lang.Float FLOAT Double or java.lang.Double DOUBLE Java.math.BigDecimal NUMERIC Java.lang.String VARCHAR byte or Java.lang.Byte TINYINT Boolean or Java.lang.Boolean

:6379> INCR N2#Self-increment(integer) 2 127.0.0.1:6379>INCR n2 (integer)3 127.0.0.1:6379>INCR n2 (integer)4 127.0.0.1:6379> decr N2#Self-reduction(integer) 3 127.0.0.1:6379>decr n2 (integer)2 127.0.0.1:6379> incrbyfloat N2 1.0#self-increment by floating point number "3"127.0.0.1:6379> incrbyfloat N2 1.0"4"127.0.0.1:6379> set N3 4.0 127.0.0.1:6379> incrbyfloat N3 2.1"6.1"127.0.0.1:6379> APPEND N3 2222#Append(integer) 7 127.0.0.1:6379>get N3"6.12222"[END]2017/7/29 16:05:41 View Code Cache

1. Notes 1. when the database field is of the blob type, the setBinaryStream (int, InputStream, int) method in PreparedStatement must be used; 2. when the database field is of the longblob type, you must use setBin in PreparedStatement. 1. Notes 1. when the database field isBlobType, must usePreparedStatementInSetBinaryStream (int, InputStream, int)Method;2. when

The work often tells a database server about JDBC connection information, not the database version, so that development is not afraid to use the latest features of the database. I wrote a small program to detect the remote database server type: Import java.sql.Connection; Import Java.sql.DatabaseMetaData; Import Java.

Text nvarchar (N) Note ntext Number (long integer) int Integer smallint Number (single precision) Real Number (Double Precision) float Number (byte) tinyint Currency Money Date smalldatetime Boolean Appendix: the script for converting to SQL. Alter table tb alter column AA byte number [bytes]Alter table tb alter column AA long number [long integer]Alter table tb alter column AA short number [integer]Alter table tb alter column AA single number [single precisionAlter table tb alter column AA dou

Use Java to access images and other types of files in the MySQL database1. Notes 1. When the database field isBlobType, must usePreparedStatementInSetBinaryStream (int, InputStream, int)Method;2. When the database field isLongblobType, must usePreparedStatementInSetBinaryStream (int, InputStream, long)Method.Otherwise, an error such as the question is thrown:Exce

Tags: and time Retrieve SQL database pos type automatic datatime readabilityDatetimeUsed when you need a value that contains both date and time information. MySQL retrieves and displays the datetime value in ' yyyy-mm-dd HH:MM:SS ' format, supported by ' 1000-01-01 00:00:00 ' to ' 9999-12-31 23:59:59 '. 8 bytes of storage.DATEWhen you need only a date value, there is no time part. MySQL retrieves and displays the date value in ' YYYY-MM-DD ' format, s

Label:--Query database allSELECT (case if A.colorder=1 then d.name else null end) Table name,A.colorder field ordinal, a.name field name,IsNull (G.[value], ") as [description]From Syscolumns ALeft join Systypes B on A.xtype=b.xusertypeINNER JOIN sysobjects D on a.id=d.id and d.xtype= ' U ' and d.nameLeft join syscomments E on a.cdefault=e.idLeft joins Sys.extended_properties G on a.id=g.major_id and a.colid=g.minor_idLeft join Sys.extended_properties

(' 1-2-31 ')--Accurate acquisition of timeSelect Sysdatetime () --Data conversion, function conversion--castSelect CAST (123 as varchar (20))-value type converted to stringSelect CAST (1.23 as int)--decimal type converted to intSelect CAST (123 as Decimal (18,2))--int type converted to decimalSelect CAST (' 1.23 ' as Decimal (18,2))--Convert string type to decimalSelect CAST (' 12.3 ' as int)--String to int --convert--Front write type, behind write original data, with cast oppositeSelect CONVE

class Enumtest {public static void Main (string[] args) {Entitymanager em = entityutil.em;String jql = "from User u";Query query = em.createquery (JQL);Listfor (User u:userlist) {System.out.println ("id=" +u.getid () + "Name=" +u.getname () + "is_locked=" +u.getislocked () + "gender=" +u.getgender () + " Level= "+u.getlevel ());}}}4. Output resultsHibernate:select user0_.id as id0_, User0_.gender as gender0_, user0_.is_locked as is3_0_, user0_.level as level0_, User0 _.name as name0_ from user

The code for database instantiation operations is optimized, and the core classes are simplified ...... This post was last edited by class nbsp; ActiveRecord { nbsp; nbs database instantiation operation code optimization, core classes are streamlined ...... This post was last edited by xjl756213616 on 16:59:50 classActiveRecord{public$table;public$data;public$obj;publicfunction__construct($table){$this->t

It's not surprising when those of us who use rails see things like 5.weeks.from_nowor3.days.ago + 2.hours. Also, PostgreSQL can do this by simply calling PostgreSQL built-in functions to achieve the same functionality.Current time/date/time stamp There are a number of ways to get the current time, and before that we need to know the following two types of differences: Always returns the current value (Clock_timestamp ()) Always returns the

Several types of database fields that are easy to remember and confusing are always incorrect. Here, take notes: A Chinese Character occupies two bytes.Char (n) contains n characters, n/2 Chinese characters (up to 4000 Chinese characters)N must be a value between 1 and 8,000. The storage size is n Bytes.Nchar (n) contains n characters and n Chinese characters (up to 4000 Chinese characters can be entered)T

Third, indexIn the previous chapter we learned to use explain to generate a query execution plan (QEP) to find the problem with the statement. Of the results returned by explain, three are index-related (possible key, key, extra), and the visible index has a prominent position in improving query efficiency.In this chapter, we will explain in all directions how to use the index to optimize our database.1. Role of the IndexThe principle of indexing is t