I want to declare a variable in SQLite and use it in insert operation.

Like in MS SQL:

declare @name as varchar(10)
set name = 'name'
select * from table where name = @name

For example, I will need to get last_insert_row and use it in insert.

I have found something about binding but I didn't really fully understood it.

3

9 Answers

SQLite doesn't support native variable syntax, but you can achieve virtually the same using an in-memory temp table.

I've used the below approach for large projects and works like a charm.

 /* Create in-memory temp table for variables */ BEGIN; PRAGMA temp_store = 2; /* 2 means use in-memory */ CREATE TEMP TABLE _Variables(Name TEXT PRIMARY KEY, RealValue REAL, IntegerValue INTEGER, BlobValue BLOB, TextValue TEXT); /* Declaring a variable */ INSERT INTO _Variables (Name) VALUES ('VariableName'); /* Assigning a variable (pick the right storage class) */ UPDATE _Variables SET IntegerValue = ... WHERE Name = 'VariableName'; /* Getting variable value (use within expression) */ ... (SELECT coalesce(RealValue, IntegerValue, BlobValue, TextValue) FROM _Variables WHERE Name = 'VariableName' LIMIT 1) ... DROP TABLE _Variables; END;

7

For a read-only variable (that is, a constant value set once and used anywhere in the query), use a Common Table Expression (CTE).

WITH const AS (SELECT 'name' AS name, 10 AS more)
SELECT table.cost, (table.cost + const.more) AS newCost
FROM table, const
WHERE table.name = const.name

SQLite WITH clause

0

Herman's solution works, but it can be simplified because Sqlite allows to store any value type on any field.

Here is a simpler version that uses one Value field declared as TEXT to store any value:

CREATE TEMP TABLE IF NOT EXISTS Variables (Name TEXT PRIMARY KEY, Value TEXT);
INSERT OR REPLACE INTO Variables VALUES ('VarStr', 'Val1');
INSERT OR REPLACE INTO Variables VALUES ('VarInt', 123);
INSERT OR REPLACE INTO Variables VALUES ('VarBlob', x'12345678');
SELECT Value FROM Variables WHERE Name = 'VarStr'
UNION ALL
SELECT Value FROM Variables WHERE Name = 'VarInt'
UNION ALL
SELECT Value FROM Variables WHERE Name = 'VarBlob';

2

Herman's solution worked for me, but the ... had me mixed up for a bit. I'm including the demo I worked up based on his answer. The additional features in my answer include foreign key support, auto incrementing keys, and use of the last_insert_rowid() function to get the last auto generated key in a transaction.

My need for this information came up when I hit a transaction that required three foreign keys but I could only get the last one with last_insert_rowid().

PRAGMA foreign_keys = ON; -- sqlite foreign key support is off by default
PRAGMA temp_store = 2; -- store temp table in memory, not on disk
CREATE TABLE Foo( Thing1 INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL
);
CREATE TABLE Bar( Thing2 INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, FOREIGN KEY(Thing2) REFERENCES Foo(Thing1)
);
BEGIN TRANSACTION;
CREATE TEMP TABLE _Variables(Key TEXT, Value INTEGER);
INSERT INTO Foo(Thing1)
VALUES(2);
INSERT INTO _Variables(Key, Value)
VALUES('FooThing', last_insert_rowid());
INSERT INTO Bar(Thing2)
VALUES((SELECT Value FROM _Variables WHERE Key = 'FooThing'));
DROP TABLE _Variables;
END TRANSACTION;

0

To use the one from denverCR in your example:

WITH tblCTE AS (SELECT "Joe" AS namevar)
SELECT * FROM table, tblCTE
WHERE name = namevar

As a beginner I found other answers too difficult to understand, hope this works

After reading all the answers I prefer something like this:

select *
from table, (select 'name' as name) const
where table.name = const.name

1

Creating "VARIABLE" for use in SQLite SELECT (and some other) statements

CREATE TEMP TABLE IF NOT EXISTS variable AS SELECT '2002' AS _year; --creating the "variable" named "_year" with value "2002"
UPDATE variable SET _year = '2021'; --changing the variable named "_year" assigning "new" value "2021"
SELECT _year FROM variable; --viewing the variable
SELECT 'TEST', (SELECT _year FROM variable) AS _year; --using the variable
SELECT taxyr FROM owndat WHERE taxyr = (SELECT _year FROM variable); --another example of using the variable
SELECT DISTINCT taxyr FROM owndat WHERE taxyr IN ('2022',(SELECT _year FROM variable)); --another example of using the variable
DROP TABLE IF EXISTS variable; --releasing the "variable" if needed to be released

Try using Binding Values. You cannot use variables as you do in T-SQL but you can use "parameters". I hope the following link is usefull.Binding Values

1

I found one solution for assign variables to COLUMN or TABLE:

conn = sqlite3.connect('database.db')
cursor=conn.cursor()
z="Cash_payers" # bring results from Table 1 , Column: Customers and COLUMN
# which are pays cash
sorgu_y= Customers #Column name
query1="SELECT * FROM Table_1 WHERE " +sorgu_y+ " LIKE ? "
print (query1)
query=(query1)
cursor.execute(query,(z,))

Don't forget input one space between the WHERE and double quotes and between the double quotes and LIKE

2

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