使用Hibernate开发租房系统（Use Hibernate to develop a rental system）.doc

使用Hibernate开发租房系统（Use Hibernate to develop a rental system） Oracle structure Server process Database read and write DBWR log LGWR program monitor PMON program stat SMON Instance structure Memory structure 300MB System global area SGA Shared pool [Shared compilation command] Data buffer [cached database files] Log buffer [temporary state logger] The cache Background process PGA The DB structure Physical structure [visible] The control file The data file The log file Physical block Logical structure hidden Table space Table stored procedure view function trigger sequence Data segment Data range A block of data Physical block Oracle basic data type The field type Chinese indicates the restrictions on other instructions The maximum length of a CHAR fixed length string is 2000 bytes VARCHAR2 variable length of string maximum length of 4000 bytes for indexing maximum length of 749 NCHAR is the maximum length of 2,000 bytes for fixed length strings based on the character set NVARCHAR2 has a maximum length of 4000 bytes based on the variable length string determined by the character set DATE DATE (day - month - year) DD - mm-yy (HHH - mi-ss) is subject to strict test and no bug LONG super LONG string maximum length 2G (231-1) is sufficient to store large work RAW fixed-length binary data with maximum length of 2000 bytes can store multimedia image sound and so on LONG RAW variable length binary data with maximum length of 2G The maximum length of BLOB binary data is 4G The maximum length of CLOB character data is 4G NCLOB has the maximum length of 4G in character data set according to the character set BFILE is stored in binary data outside the database maximum length of 4G The ROWID only row number 10 bytes of data records in the table * * * * * * * *. * * * *. * * * * format, * to 0 or 1 The maximum length of 4000 bytes of the unique row number recorded in the NROWID binary data table NUMBER (P, S) NUMBER type P is integer bit, S is decimal place DECIMAL