SQL function and feature actually, in the previous article, some basic functions of SQL commands have been mentioned, however, through SQL commands, programming designers or database administrators (DBA): (1) Establish a database for the database. (Including the space you can use) (2) Change the database system environment settings. (3) Grant user access rights for a database or form. (4) Establish an index value for the database table. (5) Modify the database table structure. (New, Delete, or Modify Table Fields) (6) Newly built data on the database. (7) Delete of data on the database. (8) Amendment to the database. (9) Query for data on the database. These items are things that can be done through the SQL command, it seems to be much more than the function represented by the two words of "Query"? SQL syntax classification is actually a lot of SQL commands, but it is necessary to use SQL to enter the god, but only a few commands are enough, because the SQL command is a syntax narrative established by the relational database, so SQL is The functions played in such databases are very strong. The following will be classified for the SQL syntax of the SQL syntax commonly used in VB. In order to explain the SQL command and before using the syntax, the classification of SQL is used below, which is included in these categories in these categories. The first class, attributes (Predicates) are used in the SQL command to indicate the way to select. Such as All, TOP and Distinct, etc. Category II, Declaration Declaration for the Name of SQL Parameter or Parameter Query, such as parameters, etc. Third categories, CLAUSEs In the SQL query, use some expressions to define the conditions of the query to narrow the range of findings, such as WHERE. The fourth class, operator (Operation) and Operations In SQL queries, integrating expressions, such as between .... and operator and Inner Join operand. The fifth category, function (function) Some SQL common functions, like AVG () is a function of the calculation average. Section 6, SQL statement (statement) SQL statement, can be said to be the main body of SQL syntax, used to issue an instruction for a particular database, and return the relevant data, and SQL syntax structure, basically using the following The child is indicated: command condition clause, for example: select * from tab where tab.name = 'a' "from .... where" is a conditional clause, in fact, SQL's syntax is not difficult, you Just remember such a rule, I believe you can learn from SQL usage.
