list of relational databases

administrator. The use command is then used to switch to the target database, and the Db.createuser () command is used to create the user with the role name "ReadWrite".There are two types of common database user roles, read and ReadWrite. As the name implies, the former can only read data cannot be modified, the latter may read and modify.Here is an example:> Use testSwitched to DB test> Db.createuser ({User: "TestUser", pwd: "Testpass", roles:["ReadWrite"]})Successfully added User: {"user": "

operations, so very slow, and the associated query is also very complex, resulting in low efficiency, often query business does not go index, query speed is very slow, mainly because of the complexity of the performance of the lower Summary Choosing a nosql requires the following 2 prerequisites:1. No acid required2. No correlation query required If you need the above two functions, you cannot select NoSQL Here are the full criteria for choosing a nosql:1 table structure is not fixed "because t

operation can be combined into an SQL statement. Take a look at the revised code: $model = new Model (); $result = mysql_query ("UPDATE goods SET quantity = quantity-1 WHERE id = 1"); Because the relational database is stored in a file, modifications to the same record cannot be made concurrently. This means that even if A and B users buy at the same time, the inventory changes are in order, so the inventory can be correctly reduced. There is also

intent lock is compatible with other locks that are lower than it. Batch update lock Batch update locks on a table allow multiple batches to load threads, load data into tables, and disallow other types of data access. Batch update locks are issued when table locking is enabled on a table, or when the table lock option is selected with a batch operation. Key Range Lock When using serializable isolation levels, key-range locks protect a range of rows that are implied in the result set and are no

performance of the system and various database management operations, including the followingComputing performance of--oracle database--Performance of database access operations--performance of backup and operation4. Create and open a databaseUsing DBCA5. Backing Up the databaseManufacturers have integrated, but need seamless backup recovery must be optimized for processing6. Registering Database UsersCreate users, assign permissions and roles7. Implementing Database DesignCreate table spaces t

characteristics are suitable for use with serialization isolation (serializable isolation):1, the data volume is large, but the transaction is short, only will update the database with less data rows2, two concurrent transactions the probability of modifying the same data is small3. A transaction with a relatively long run time only performs read-only operationsThis paragraph I see not quite understand, one is the transaction level of the read consistency, one is the sentence level of read cons

This ranking is based on the DB engines list, which analyses 200 different databases on the market, listing top 10. Undisputed Top 3 Oracle, MySQL, and Microsoft SQL Server have been occupying the top three of the rankings with absolute advantage, carving out the largest number of users in the market with unique advantages. 1. Oracle 11g First release : 1980 Licensing mechanism : proprietary whether S

Topics: Listing code for all libraries on SQL Server First: dbo permissions list all databases on the server Copy Code code as follows: Dim SRV Dim Objdb Set srv = Server.CreateObject ("SQLDMO.") SQL Server ") Srv. LoginTimeout = 15 Srv. Connect "127.0.0.1", "Lcx", "LCX" Set objdb = Server.CreateObject ("SQLDMO. Database ") %> For each objdb in SRV. Dat