Data provided by user as well as data generated during or as a result of processing is stored in computer’s memory (RAM) which is temporary in nature. We can get a high level description of how a SQL query is internaly executed.Python Tutorial By KnowledgeHut Any computer program requires data for processing. INSERT INTO CASHIER VALUES ("foo","bar") If we write a SQL script in a file named example.sql like this:ĬREATE TABLE CASHIER (name VARCHAR(10) PRIMARY KEY ,pass VARCHAR(10) NOT NULL) $ sqlite3 foo.db "INSERT INTO CASHIER VALUES (\"foo\",\"bar\") " If something was wrong you can roll back the transaction instead of committing it. Sqlite> UPDATE ANALUX SET Difficulty = (SELECT Difficulty FROM BLOCK WHERE BLOCK.Height = ANALUX.Height) If we want to fill Difficult column with data from other table e.g: BLOCK where Height is primary key for both tables: Sqlite> ALTER TABLE ANALUX ADD Difficulty REAL DEFAULT NULL ĬREATE TABLE ANALUX (Height INTEGER PRIMARY KEY ,Price REAL DEFAULT NULL ,Difficulty REAL DEFAULT NULL) We add a new Difficulty column to this table:ĬREATE TABLE ANALUX (Height INTEGER PRIMARY KEY ,Price REAL DEFAULT NULL) Sqlite> alter table CASHIER rename to CLIENTS Sqlite> INSERT INTO CLIENT (name,value,state,address) SELECT name,value,-1,address FROM CLIENT_OLD Sqlite> INSERT INTO CLIENT SELECT * FROM CLIENT_OLD Ĭolumns returned by select have to match elements expected by insert.Ĭopy some contents from a table into another one: SQL As Understood By SQLite (On conflict)Ĭopy contents from a table into another one: Sqlite> INSERT OR REPLACE INTO VARS (name,value) VALUES('color', 'blue') Insert a row in a table, but if a conflict arises because of a UNIQUE or PRIMARY KEY constraint then replace that row: Sqlite> INSERT INTO VARS (name,value) VALUES('color', 'blue') Sqlite> select * from CLIENTS ORDER BY Name DESC LIMIT 3 This LIMIT keyword can be used along ORDER BY to specify a column to order results. Show contents of a table limiting number of rows in the result: Sqlite> CREATE TABLE IF NOT EXISTS VARS (name VARCHAR(128) PRIMARY KEY ,value VARCHAR(512) NOT NULL) Sqlite> CREATE TABLE VARS (name VARCHAR(128) PRIMARY KEY ,value VARCHAR(512) NOT NULL) Ĭreate the table only if it does not already exist: We can access client database tables preceded by 'client.' prefix. database command shows client database too. Sqlite> ATTACH DATABASE 'client.db' AS client Other types like VARCHAR(N), DECIMAL(N, M) are assimilated to the former storage classes by their affinity (VARCHAR to TEXT, DECIMAL to INTEGER), so their limits (N, M.) are not enforced.Īttach another database (client) from other file (client.db): TEXT: a text string, stored using the database encoding (UTF-8, UTF-16BE or UTF-16LE).īLOB: a blob of data, stored exactly as it was input. REAL: a floating point value, stored as an 8-byte IEEE floating point number. INTEGER: a signed integer, stored in 1, 2, 3, 4, 6, or 8 bytes depending on the magnitude of the value. List all databases and their associated files:ĬREATE TABLE "PRODUCTS" (Id INTEGER PRIMARY KEY AUTOINCREMENT ,TStamp INTEGER NOT NULL ,Name VARCHAR(60) NOT NULL ,Price DECIMAL(10,5) NOT NULL) If TABLE specified, only dump tables matching databases List names and files of attached databases clone NEWDB Clone data into NEWDB from the existing database bail on|off Stop after hitting an error. backup ?DB? FILE Backup DB (default "main") to FILE Sqlite3 is the command line interface for SQLite version 3. SQLite is a database engine contained in a C library that usually stores its data in a file.
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