How to check if TABLE exists before ALTER query? - sqlite

Before adding (ALTER) new column to table I want to check if that table exists. Because app is crashing since table is not present and we tried to add column to it.
I tried "Alter table if exist table_name add column abc" but no luck.
I want to do this in 1 query.

Related

SQLite Copy Table Content from one Table to another Table and Update

I have two SQLite files, each of them has one table and the same table design. One Column is set as Primary Key. I want to copy all data from ItemsB into ItemsA. All data should be updated. The ItemsB Table is the newer one.
I've tried:
ATTACH DATABASE ItemsB AS ItemsB;
INSERT INTO ItemsA.PMItem (ItemID,VarID,Name1) SELECT ItemID,VarID,Name1 FROM ItemsB.PMItem;
Obviously this can't work due the Primary Key (which is the column VarID).
Then I tried it with ON CONFLICT:
ON CONFLICT (VarID) DO UPDATE SET Name1=excluded.Name1
But this won't work either.
Example Table:
CREATE TABLE PMItem (
ItemID INTEGER,
VarID INTEGER PRIMARY KEY,
Name1 TEXT
);
You need a WHERE clause with an always true condition, to overcome the ambiguity that is raised when ON CONFLICT is used after a SELECT statement:
INSERT INTO PMItem (ItemID,VarID,Name1)
SELECT ItemID,VarID,Name1
FROM ItemsB.PMItem
WHERE 1
ON CONFLICT(VarID) DO UPDATE
SET Name1 = EXCLUDED.Name1;

Insert into table access 2010

How can i copy contents of my whole table in sql access and update one column to the same table.
So basically is selecting the whole table and updating one column and pasting that to the same table. thanks.
To clone an existing table back into the same table, but using a different value for one field, use something like the following (see notes that follow!):
INSERT INTO Table1 ( FldA, FldB, MyDate, StateCode )
SELECT Table1.FldA, Table1.FldB, Table1.MyDate, "FL" AS Expr1
FROM Table1;
You can't easily use the * to select/update all fields because your need to change one field would result in a "duplicate destination" error. If needed, you could use an 'IF' statement to change to different values (i.e. IF(FldA="VA","FL",IF(FldA="MD","TX",Flda))

Altering and adding column to the table in sqlite3

If I alter the table and add a new column will add the data be wiped off from that table.
ALTER TABLE MyTable ADD COLUMN noOfDays integer default 0 NOT NULL
Will the above SQL command drop MyTable and then ALTER it with the noOfDays column or will it simply add the noOfDays column without dropping it.
No, add just adds the column. Neither its data will be deleted nor the table be dropped.
p.s. from the documentation
"Note: also that when adding a CHECK constraint, the CHECK constraint is not tested against preexisting rows of the table." (check SQLite manual for more)

create table with constraints from another table in sqlite?

I want create table from another table with constraint?
I used this query "create table destination as select * from source;" fro table creation.
But its copy only the column name in table without column constraint.
There is a special table named sqlite_master, holding the full CREATE TABLE statement for each table (it's modified as appropriate during ALTER TABLE).
I would make my application retrieve that CREATE TABLE statement:
SELECT sql FROM sqlite_master WHERE type='table' AND name='source';
Then I would replace the table name right after CREATE TABLE tokens, and execute the result as a new sqlite query.
I don't think that it's possible to do in sqlite's pure SQL without extensions.

SQLITE : How to add several columns to a table?

Hi In my application I am using SQLITE database,
I want to add multiple column in table,
If i am adding one column that work fine,
I am using ALTER table for add new column,
With this i am able to update one column,
ALTER TABLE "main"."tblCredit" ADD COLUMN "CardDetail" VARCHAR
But How can i add multiple column in tblCredit table.
Use repeated calls to ALTER TABLE.
You should not have to do this too often anyway.
IN DB2
with the help of alter command add multiple column in table
ALTER TABLE TABLE_NAME ADD COLUMN F_NAME VARCHAR(30)
ADD COLUMN L_NAME VARCHAR(30)
ADD COLUMN ROLL_NO INTEGER
ADD COLUMN MOBILE_NUMBER VARCHAR(12);

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