effective oracle by design

First, the overall analysisThe implementation of this system is not difficult, but how to better design the implementation method or need more in-depth analysis, such as: If you add additional functionality, is not required to changeThe code is very small, just add a little bit of functionality directly to it? What if you're using a MySQL database instead of Oracle? This should be considered clearly at the

Tags: conditional can gen index How many statement efficiency fields are automaticallyPrefix nature:The prefix of a composite index is that the index is used only if the first field of the composite index appears in the predicate condition of the SQL statement.If the composite index is (ename,job,mgr), you can use a composite index as long as the first field ename appears in the predicate condition, otherwise it will not be used.The only exception is the skip Scan index, which is automatically s

Risks of incorrect selection of Oracle Database Design Field Types An Oracle data type is inaccurate. We will construct a table storage date field, a storage varchar2 field, and a storage date field for a test. I have also written the following: Problems caused by inconsistent field type design and actual business SQL>

oracle| Design | data | Repeat we may have this situation, a table originally poorly designed, resulting in the table data data duplication, then, how to delete the duplicate data? Duplicate data may have two scenarios, the first one being only some of the fields in the table, and the second is exactly the same as two rows of records. One, for partial field duplicate data deletion Let's talk about how to

number default + NOT NULL); test data (user) insert into users values (' WxH ', ' wxh ', ' [email protected] ', ' 455 ', 1); commit; self-growth create Sequence Book_seqstart with 1increment by 1minvalue 1maxvalue 9999999nocyclenocache; test data (product) insert into book values (book _seq.nextval, ' JSP application development ', ' small Wind ', ' electronics Press ', 59,400, insert into book values (Book_seq.nextval, ' JAVA WEB development ', ' Little Yellow ', ' Electronic industry Press ',

The concept of partitioning tables and tablespaces is distinguished between the design of Oracle partition tables: tablespace: A table space is a collection of one or more data files, all of which are stored in the specified table space, but are primarily stored in tables, and are therefore called table spaces.partition Table : Partitioning is dedicated to resolving key issues that support large tables and

Size944 Bytes sent via sql*net to client349 bytes received via sql*net from client3 sql*net roundtrips To/from Client0 Sorts (memory)0 Sorts (disk)Rows processedSummary: Although the two SQL consumes the same resources, but the SQL1 evaluation results are not correct, in the Multi-table association, this is definitely a hidden danger, it is very easy to lead the execution plan go wrong. In addition to the above reasons, there is still the problem is that using VARCHAR2 to save the date will cau

Label:1. If you use powerdesigner such a tool, be careful to remove the double quotation marks from the table in the exported SQL statement for the tool.2. When building tables and building fields, use underscores between different words, such as rec_id3. The numeric Type field in Oracle, you should determine the precision, when using MBG reverse generation, you can determine whether it is an integer or BigDecimal.4. NVARCHAR2 and NVARCHAR2 in

Table is one of the most basic objects in an Oracle database. The base object for a database is very important for a high-rise building from the ground up. Because the design is reasonable, directly related to the performance of the database. From Oracle database rookie to database expert this process, in table design

Partition Table Concept Partitioning is committed to solving the key issues that support large tables and indexes. It uses a small and easy-to-manage partition-based piece (piece) method. Once a partition is defined, SQL statements can access a partition rather than the entire table, thus improving management efficiency. Partition for Data Warehouse applications Program Very effective because they often store and analyze massive amounts of historic

The non-update principle in Oracle Database Design when adding data, if the new logic involves the original information, try not to update the data. Www.2cto.com. What kind of situation will there be such a problem? For example, a user places an order. If you have purchased orders in the past, this order will be discounted, but the original order can only be discounted once at a time. A-> B-> C has two

1, in the Powerdesinger design table (1) After downloading Powerdesinger, right key new-->physical data model default name is: Physicaldiagram_1, right key new-->table, start table design (2) Configuring an ODBC data source Configure the ODBC data source in your computer's control Panel \ System and security \ Management Tools (my W7 system). After selecting the database drive and connection pool, click Add

Introduction Oracle is the most widely used large-scale database management system, improve the efficiency of Oracle database system, is the premise and guarantee of the efficient operation of the whole computer information system. There are many factors affecting the performance of Oracle database application system, including software factors, hardware environ

ll,51 userid VARCHAR2 (Ten) not null,52 power_count number (3,2) not null,53 Power_time Date not null,54 power_status number (1) not null,55 Power_priceid varchar2 (+) Not null,56 power_beforecount number (3,2) not null,57 constraint Pk_power primary KEY (POWER_ID) Comment on column power.power_id is ' meter number ', comment on column water.userid is ' user number '; Comment on column P Ower.power_count is ' meter run '; Comment on column power.power_time is ' meter time ';

,uno,uname,phone,address)If you use SNO as the key column, Sanme,uno is directly dependent on Sno, but Uname,phone,Address these three columns are directly dependent on UNO, indirectly dependent on SNO, so this design does not conform to the3NF, should be redesigned to:R1 (Sno,sname,uno), a table for student informationR2 (uno,uname,phone,address), a table for university information------------------------------------------------------------DDL (Creat

edit_tag_time date" sysdate {data record creation date}{}{} catalog metadata file_cataloguemetadata catalogueid catalog number varchar2 50 no Yes {catalog number}{}{} file_catalogue id catalog metadata file_cataloguemetadata metadataid meta Data number nvarchar2 50

The concept of partitioning tables and tablespaces is distinguished between the design of Oracle partition tables: tablespace: A table space is a collection of one or more data files, all of which are stored in the specified table space, but are primarily stored in tables, so they are called table spaces.partition Table : Partitioning is dedicated to resolving key issues that support large tables and indexe

: Network Disk DownloadContent IntroductionEditing the volume of information contained in this book can improve your programming skills to a new level. You'll learn how to write dynamic PL/SQL programs and Oracle database interfaces, perform complex computations, and use advanced techniques to control error conditions. In addition, you will receive up-to-date information on Pl/sqltoolkit,java integration and performance optimization.

The concept of partitioned tables Partitions are committed to resolving key issues that support large tables and indexes. It uses the method that they decompose into smaller and manageable slices called partitions (piece). Once a partition is defined, the SQL statement can access one partition rather than the entire table, thereby increasing the efficiency of the administration. Partitioning is very effective for data warehouse applications because t

of decimal digits in seconds, and the range of values 0~9. Optional.7. LobClob/blob implementation is more complex, here only to mention a few and performance-related points, of course, can not use the LOB as far as possible: A, a LOB field including Lobindex and LOBSEGMENTB, lob default can be stored in the Table (table field), the condition is: 1. Its size is less than 4KB 2. And is not used at the time of definition (disable storage inrow) sentence (the default is enable) when the LOB is gre