mysql declare variable in query

1.cursor CursorsUsed to declare a data setThe declaration of the cursor must be after the variable and the condition declaration, before the handler declarationCursor Properties: Insensitive: The server can or does not replicate its results

Document directory Lifecycle 2.8. DECLARE statement Both SQL server and mysql are our frequently used database systems. Next we will introduce the differences between the values of SQL server and mysql variables, and hope to enlighten

When mysql is imported into the stored procedure, the declare error is solved. When importing the stored procedure, the following DECLARE errors are often encountered :? ErrorCode: 1064 YouhaveanerrorinyourSQLsyntax;

in MySQL, we can save a value or a query result in a user-defined variable, and then in the following statement in the application. set defines variables;SET @var_name: = expr [, @var_name = expr] ....SET @var_name = expr [, @var_name = expr]

Variable assignment in mysql, mysql variable assignment Http://www.cnblogs.com/qixuejia/archive/2010/12/21/1913203.html   Variables in SQL server must be affirmed first and then assigned values: The local variables are identified with one @ and the

Tag: color is medium tar local str local SSI GlobalDescription: Now on the market defined variables of the tutorial and books are basically stored procedures are described, but the stored procedure variables can only be used in begin...end block,

Server system Variables (System variable)The MySQL system variable (systems variables) refers to the various system variables of the MySQL instance, which are actually some system parameters that are used to initialize or set the database to occupy

In MySQL5, the new statement declare is used. in the composite statement, the variable declaration command is DECLARE. (1) Example with two DECLARE statements Two DECLARE statements Create procedure p8 () BEGIN DECLARE a INT; DECLARE B INT; SET a =

Why queries are slow Slow Query Basics: Optimizing data access Verifying that an application is retrieving a large amount of data that is more than needed usually means accessing too many rows, but sometimes it may be too many columns

In common: case-insensitive, both variables Different points: Global variables are read-only in the system and can be modified in a configuration file Terminology classification for MySQL variables: 1. User variable: Starting with "@" in the form