SQLite add Primary Key

Jack_61663 0
Viewed 162192

I created a table in Sqlite by using the CREATE TABLE AS syntax to create a table based on a SELECT statement. Now this table has no primary key but I would like to add one.

Executing ALTER TABLE table_name ADD PRIMARY KEY(col1, col2,...) gives a syntax error "near PRIMARY"

Is there a way to add a primary key either during table creation or afterwards in Sqlite?

By "during creation" I mean during creation with CREATE TABLE AS.

sqlite
10 Answers

You can't modify SQLite tables in any significant way after they have been created. The accepted suggested solution is to create a new table with the correct requirements and copy your data into it, then drop the old table.

here is the official documentation about this: http://sqlite.org/faq.html#q11

user_983890

You can do it like this:

CREATE TABLE mytable (
field1 text,
field2 text,
field3 integer,
PRIMARY KEY (field1, field2)
);
user_1081300

CREATE TABLE tablename( Column1 INTEGER PRIMARY KEY, Column2 VARCHAR(50) )

INSERT INTO tablename SELECT Column1 , Column2 FROM ANOTHERTABLE

user_196894520

I used the CREATE TABLE AS syntax to merge several columns and encountered the same problem. Here is an AppleScript I wrote to speed the process up. 

set databasePath to "~/Documents/Databases/example.db"
set tableOne to "separate" -- Table from which you are pulling data
set tableTwo to "merged" -- Table you are creating
set {tempCol, tempColEntry, permColEntry} to {{}, {}, {}}
set permCol to {"id integer primary key"}

-- Columns are created from single items  AND from the last item of a list
-- {{"a", "b", "c"}, "d", "e"} Columns "a" and "b" will be merged into a new column "c".  tableTwo will have columns "c", "d", "e"

set nonCoal to {"City", "Contact", "Names", {"Address 1", "Address", "address one", "Address1", "Text4", "Address 1"}, {"E-Mail", "E-Mail Address", "Email", "Email Address", "EmailAddress", "Email"}, {"Zip", "Zip Code", "ZipCode", "Zip"}, {"Telephone", "BusinessPhone", "Phone", "Work Phone", "Telephone"}, {"St", "State", "State"}, {"Salutation", "Mr/Ms", "Mr/s", "Salutations", "Sautation", "Salutation"}}

-- Build the COALESCE statements
repeat with h from 1 to count of nonCoal
set aColumn to item h of nonCoal
if class of aColumn is not list then
    if (count of words of aColumn) > 1 then set aColumn to quote & aColumn & quote
    set end of tempCol to aColumn
    set end of permCol to aColumn
else
    set coalEntry to {}
    repeat with i from 1 to count of aColumn
        set coalCol to item i of aColumn as string
        if (count of words of coalCol) > 1 then set coalCol to quote & coalCol & quote
        if i = 1 then
            set end of coalEntry to "TRIM(COALESCE(" & coalCol & ", '') || \" \" || "
        else if i < ((count of aColumn) - 1) then
            set end of coalEntry to "COALESCE(" & coalCol & ", '') || \" \" || "
        else if i = ((count of aColumn) - 1) then
            set as_Col to item (i + 1) of aColumn as string
            if (count of words of as_Col) > 1 then set as_Col to quote & as_Col & quote
            set end of coalEntry to ("COALESCE(" & coalCol & ", '')) AS " & as_Col) & ""
            set end of permCol to as_Col
        end if
    end repeat
    set end of tempCol to (coalEntry as string)
end if
end repeat

-- Since there are ", '' within the COALESCE statement, you can't use "TID" and "as string" to convert tempCol and permCol for entry into sqlite3. I rebuild the lists in the next block.
repeat with j from 1 to count of tempCol
if j < (count of tempCol) then
    set end of tempColEntry to item j of tempCol & ", "
    set end of permColEntry to item j of permCol & ", "
else
    set end of tempColEntry to item j of tempCol
    set end of permColEntry to item j of permCol
end if
end repeat
set end of permColEntry to ", " & item (j + 1) of permCol
set permColEntry to (permColEntry as string)
set tempColEntry to (tempColEntry as string)

-- Create the new table with an "id integer primary key" column
set createTable to "create table " & tableTwo & " (" & permColEntry & "); "
do shell script "sqlite3 " & databasePath & space & quoted form of createTable

-- Create a temporary table and then populate the permanent table
set createTemp to "create temp table placeholder as select " & tempColEntry & " from " & tableOne & ";  " & "insert into " & tableTwo & " select Null, * from placeholder;"
do shell script "sqlite3 " & databasePath & space & quoted form of createTemp

--export the new table as a .csv file
do shell script "sqlite3 -header -column -csv " & databasePath & " \"select * from " & tableTwo & " ; \"> ~/" & tableTwo & ".csv"
user_11913010
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