Example of Describing Tables in SQLiteįirst, create a table by using the create table statement. It is NULL for the internal indexes these are automatically created by PRIMARY KEY or UNIQUE constraints. The text in the sqlite_schema.sql column is a copy of the original CREATE statement text that was created however, it normalized as described before and as modified by proceeding ALTER TABLE statements. This means we can create triggers that can be executed against the database. We represent it as sqlite_schema_rootpage. The root page is used to store the page number of the root tree page for the table and index. We can represent tbl_name as sqlite_schema_tbl_name. Tbl_name is used to store the table name or the view name. However, we can’t use the primary key constraint with the rowid table, so sqlite_schema does not allow primary, but SQLite auto index uses the primary key. Here, we can also specify unique and primary key constraints at the table creation time. name specifies the column store name of the object. We can represent the type as sqlite_schema.type. Type means text string such as view, index, table, or trigger since it depends on which type of object is defined. When we talk about the Schema Table, the schema uses different parameters such as type, name, tbl_name, root page, and SQL. They are associated with every database connection. Here the last two alternatives are used for the temp database. The sqlite_schema is a reference for the schema table and has some alternative names such as sqlite_master, sqlite_temp_schema, and sqlite_temp_master. The sqlite_schema contains a single row for each table, index, view, and trigger in the schemas except when there is no entry for the sqlite_schema table itself. If users do modify it, they have to bear the risk of database corruption. Under normal conditions, there is no need to modify it. SQLite creates the schema table when the database is created and continues to modify its content as the SQLite users submit statements for execution. The syntax to describe a table is the following:ĬREATE TABLE sqlite_schema( type text, name text, tbl_name text, rootpage integer, SQL text ) SQLite allows the description of the table in different ways. Describing the tables essentially means that we can print specific details of all the columns in the table, such as column name, the data type of the column as well as the size of the column. schema command is a command line program that we can use to get a detailed structure of the required table. schema command to describe a table in the database. SQLite is a relational database management system that employs many commands at the user’s disposal. This allows the user to see a detailed structure of the table. One of these commands is the describe command. SQLite comes equipped with several different commands for its users. It has built-in mobile phones, most computers, and various applications worldwide. This software is quite popular throughout the world. db files are in the same path.So rechnest du mit Restwert! Python Built-Ins | #Shorts In this way, the Python file writes to and the SQLite shell reads from. If you work in Windows, I think it might be useful to move this sqlite.exe file to same folder with the other Python files. To see all tables in the database you have previously chosen, type the command. In other words use "c:/work/ex1.db", not "c:\work\ex1.db". Use forward-slashes as the directory separator character. You might want to use a full pathname to ensure that the file is in the directory that you think it is in. The example above causes the database file named "ex1.db" to be opened and used, and created if it does not previously exist. To use a persistent disk file as the database, enter the ".open ex1.db" command immediately after the terminal window starts up. When it is initialized, by default this SQLite session is using an in-memory database, not a file on disk, and so all changes will be lost when the session exits. Besides, if you are using Windows OS and do not know where the command shell is, that is in the SQLite's site:Īfter downloading it, click sqlite3.exe file to initialize the SQLite command shell. You can manipulate your database using the commands described in this link. So to get a list of all tables in the database, use the following SELECT command: SELECT name FROM sqliteschema WHERE type'table' ORDER BY name For indices, type is equal to 'index', name is the name of the index and tblname is the name of the table to which the index belongs. Since nobody has mentioned about the official reference of SQLite, I think it may be useful to refer to it under this heading:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |