Database Administrator

Oracle Table Function is introduced in Oracle9i, which is perfectly compatible with the advantages of view and stored procedure: Example: 1. Table () function: set feedback offcreate or replace type type_int_date_varchar2 as object (i integer, d

The problem is as follows: Assume that the information is stored in the mysql database. As shown in the following figure, the information heap of Table A is A million-level information heap (each piece of information is not long and generally 20

When writing an SQL statement into a database To_date ('20140901', 'yyyymmddhhmms ') Reporting ORA-01810: The format code appears twice The reason is that the year, month, and day expressions in java are different from those in oracle.

-- Create tablecreate table policycompany (ID VARCHAR2 (32) default SYS_GUID () not null, FLOWID VARCHAR2 (50), conpanyid number, ISCOMMUNICATION VARCHAR2 (10 )) tablespace USERS pctfree 10 initrans 1 maxtrans 255 storage (initial 64 K minextents 1

The concept of Partitioned Tables and tablespaces is distinguished between Oracle partition tables: Table space: A table space is a collection of one or more data files. All data objects are stored in the specified table space. Partition Table:

Original article. For more information, see the source! I recently learned about Apache, Mysql, and php on Mac. Record it here for memo 1 php1.1 php Return Value Test If the test is successful under MAMP, echo returns the data directly.1.2 php

Preface 1. the relational model requires that the relationship must be normalized. the most basic of these normative conditions is that each component (tuples) of the relationship must be an attribute of an unidentifiable data item. 2. The mode

Reprint please indicate the source: http://blog.csdn.net/u012860063? Viewmode = contents Problem description: As China's economy is developing rapidly, the amount of vehicle ownership has also increased significantly, and the congestion in cities is

During the interview, you will be asked a variety of strange questions. You may be able to give the most perfect solution from the actual point of view when thinking about the solution. The following is a database-related interview question:

You need to select the latest merchant update timestamp at intervals: Update DP_Shop set DP_Shop.LastDate = now () where DP_Shop.ShopId in (select ShopId from DP_Shop order by LastDate limit 5 ); ERROR 1235 (42000): This version of MySQL doesn't

There is a ticket for the expansion process based on the CRM system. In the database, tc_worksheettc_worksheet_1_1 tc_worksheet_attr tc_worksheet_mattr tc_worksheet_xattr. The ticket data is stored in the preceding tables at the same time.  

Preface The database is the repository of the program and the most vulnerable part of the program. Because of its vulnerability and importance, it needs to be managed and optimized specially. In today's network era, database flexibility and

1. delimiterDelimiter is the mysql separator, and the default delimiter In the mysql client is semicolon (;). If many statements are input at a time and there is a semicolon in the middle of the statement, a special separator needs to be specified.2.

-- The trace file is read INTO the table for analysis. SELECT * into zgsjyfrom fn_trace_gettable ('e: \ wxxcdbprofiler. trc ', default); -- SQLselect TOP 100 SUBSTRING (Textdata, 1,660) as 'name', count (*) as 'number' in a certain period of time ',

MySQL supports multiple column types: numeric, date/time, and string (character. This chapter first gives an overview of these column types, and then describes in more detail the types of various columns and the summary of column type storage

1. Inner connectionJoin)An internal connection is the most common connection. Its page is called a common connection, and E. FCodd was first called a natural connection.ANSI SQL-92 standards belowSelect *From t_institution IInnerJoinT_teller tOn I.

1. If you can use DISTINCT, you do not need group.SELECT OrderID FROM Details WHERE UnitPrice> 10 group by OrderIDCan be changed to: select distinct OrderID FROM Details WHERE UnitPrice> 102. Do not use UNION if union all is used.Union all does not

1. is null and IS NOT NULLNull cannot be used as an index. Any column containing null values will not be included in the index. Even if there are multiple columns in the index, as long as one of these columns contains null, this column will be

1. select an appropriate data typeSelect the minimal data type for the columnIf the text length in a column is different, use VARCHAR instead of CHARDo not use NVARCHAR or NCHAR if Unicode is not storedIf the length of a row cannot exceed 8000, use

A ORA-00997 is reported when you access the long field of a table through dblink. for example, I want to access the remote ELISDATA through dblink. in the POS_TEST_CASE_AMASS table, where the CASE_PARAM_CHAR field is LONG, some conversions are