jira summary field

I was bored today. I imported the Jira database (MySQL version) and checked it in navicat. Summarize the following points: I. Various types: Tables: N Views: 0 Functions: 0 Trigger: 0 Ii. Foreign Key Usage: Foreign keys are rarely used in table design. Except for a set of tables that appear to be automatically generated, there are basically no foreign keys. There is a lot of debate over the use of foreign keys on the Internet:

applies to modifyingALTER TABLE ' table_name ' change ' column_name ' column_name ' type (longth) UNSIGNED null DEFAULT null COMMENT ' comment ' 7. Adjust the order of the fields:ALTER TABLE table nameChange field name new field FirstName type default after field name (after which field is skipped)Example:

table change before field names modified field name int (one) not NULL,Change before field names modified field name int (one) not NULL,Change before field names modified field name int (one) not NULL,Change before

Mysql field type summary --- field type summary table original Web site: http://kimbriggs.com/computers/computer-notes/mysql-notes/mysql-data-types-50.file Type {storage} Name Range Attributes Default Numeric{1 byte} TINYINT [(M)] -From 128 TO 127[0 to 255 if UNSIGNED] AUTO_INCR

There is a large amount of data in the MySQL table, but a summary of the field needs to be read. For example, this field is primarily used to store articles, and this field of all records for this table is very long. The efficiency of the Select Title,content from article when querying is much worse than the select ti

MySQL Partition Scheme Summary based on the time field, mysql Field MySQL supports four partition types: RANGE, LIST, HASH, and KEY. RANGE can be divided into Native RANGE and range columns. LIST is divided into Native LIST and list columns. HASH is divided into Native HASH and linear hash, and KEY includes native KEY and linear hash. The differences between thes

our fight is over ... It's still hard to think about it now.DfghD Mark God told me this question, feel very can do, but efficiency is not guaranteed. On a queue of priority. TLE ... And then put it down ... And then didn't pick up. Think of the way after the game to hear the merge ...F Chew for a long time, DP direction is right, a few dimensions of the definition of a problem, with the team-mates and no results at the end of the final thought of a beautiful search who know will not a stop theG

internal structure of the computer, the members of the bit domain from a byte from the low to high storage.Iii. Union:The format can be seen in the following example, there are three points to note:1. All members of the Union share a common memory, and the change of one member changes the value of all other members.2. The first address of all members is the same.3. The alignment satisfies all members.See Example:Union value{ char s[9]; int N; Double D;} data; // its size is 16. The s

-encoding is consistent with the Vary header value of the previous response, that is, whether the same content encoding method is used, which prevents the cache The server responds to the compressed entity in its own Cache to a browser that does not have the ability to decompress. Example: vary:accept-encoding31. Via: Lists the proxies from the client to the OCS or in the opposite direction, and what protocol (and version) they are using to send the request. When the client request arrives at th

"sorted fields" ASC defaultDescending: Oredr by "sorted field" descSort multiple fieldsSelect Bname,price from books where Price in (50,60,70) Order by Price Desc,bname desc;Summary of data additions and deletions in tableThe SELECT statement returns 0 or more records, a record read operationInsert, UPDATE, delete only returns the number of records affected by this operation;Functions in the MySQL database

and the original type to be modified, create a new field to transfer indirectly. Second, new fields Syntax for new field: ALTER TABLE tablename Add (field name type [default Value][null/not null],....);1. Add a field:ALTER TABLE test1 Add (name VARCHAR2 () default ' anonymous ' not NULL); 2. Add three fields using one SQL statement at a time:ALTER TABLE test1 Ad

This article mainly introduces the MySQL data type and common field attribute summary. This article summarizes the date and time data types, numerical data types, string data types, and so on. For more information, see Preface For example, in C ++, how many bytes are required to define the int type and how many bytes are required to define the double type. MySQL strictly controls the data in each column of

. The TestGetOrderById2 method and the TestGetOrderById3 method can get the desired result normally after executing the query.SummarizeThe test code above demonstrates that when the attribute names in the entity class are inconsistent with the field names in the table, the query operation with MyBatis cannot be queried for the corresponding results and the two approaches to the problem are as follows:Workaround One : through the query in the SQL The

There is a table named TB, field segment named Name, data type nchar (20).1. Assuming that the field data is empty, you can do it directly, regardless of the field type you are changing to:ALTER TABLE TB Modify (name Nvarchar2 (20));2, if the field has data, then to NVARCHAR2 (20) can be directly executed:ALTER TABLE T

One table is named tb, the field segment is named name, and the data type is nchar (20 ).1. If the field data is empty, you can directly execute the following command regardless of the field type:Alter table tb modify (name nvarchar2 (20 ));2. If the field has data, you can change it to nvarchar2 (20) and execute it di

Background:As a programmer, the technology around us is constantly being upgraded.Take the web, the first only HTML, then have CSS, and then have Ajax and so on. Now the total amount of knowledge accumulated in web development is very large. So much knowledge to learn swarmed, it is easy to let us at a loss, do not know where to learn from, like a headless fly.Recently, there have been other lab classmates came to me to ask how to get started a new field