In Node.js I created a DATETIME string for in my sqlite3 database using moment.js and I formatted it
moment().format('YYYY-MM-DD h:mm:ss')
Never needed that column until after this project and I want to do some calculations. Turns out I should have formatted using 'hh', or two decimals for the hour (eg. '09' instead of '9') because sqlite3 otherwise won't see it as a valid DATETIME entry. Now I have 20k entries with a tonload of invalid DATETIME entries, argh!
What would be an efficient way to update all the entries in this column to valid sqlite3 DATETIME entries? Is it possible through just SQL?
This may work:
UPDATE t SET d = SUBSTR(d,1,11) || '0' || SUBSTR(d,12) WHERE LENGTH(d) = 18;
Related
How can I convert timestamps to dates in SQLite?
The following code only produces a Timestamp column and a Date columns with NULL values. The the SQL code needs to convert from a "08/28/2020 8:00" format.
SQL CODE:
'''Select Timestamp, strftime('%m-%d-%Y', Timestamp) as Date
FROM Room_Data'''
The SQLite documentation is pretty clear, but I can't seem to get the desired result.
The strftime is meant to format a date, rather than perform conversion.
In the meantime you could try something like that to gather the pieces:
SELECT Timestamp,
SUBSTR(c,7,4) || '-' || SUBSTR(Timestamp,1,2) || '-' || SUBSTR(Timestamp,4,2) as Date
FROM Room_Data
Since SQlite doesn't really have the concept of a date, unlike other DBMS, the best choice would be to convert your dates to integer, either as Unix timestamps or in string form (YYYY-MM-DD) but storing dates as integer like 20201010 would be acceptable too.
NB: be careful with names like Timestamp or Date, they are reserved keywords in many programming languages and DBMSes.
The original code won't work in Windows 10 for some reason. Trying this from a Linux distro (Kubuntu, in this case) seems to resolve the issue. In Windows, the date needs to be converted to a '2020-01-01' format to actually work.
SQLite is amazing, but not sure why functionality changes for Windows 10. Feel free to comment if you know more about the differences.
can you please help me why this code does not work?
I dont understand why the result include "2017".
SQLLITE
QUERY
SELECT issue_date as count FROM tablename where issue_date >= "08/08/2016" and issue_date < "09/01/2016"
Result
"08/08/2017"
"08/11/2017"
"08/18/2017"
"08/18/2017"
"08/22/2017"
"08/22/2017"
"08/28/2017"
"08/31/2017"
Create query
CREATE TABLE tablename (
issue_date datetime text not null
}
Insert query
INSERT INTO tablename (issue_date) values ("08/31/2017");
You are storing your dates in a non ANSI compliant format. As there is no formal date type in SQLite, and all dates are essentially stored as strings, your current date comparison will behave and sort as if you are comparing to text. It won't work, because you have the month first, followed by the day, followed by the year. To get text comparisons of dates to work correctly, use a format something like this:
yyyy-mm-dd
You should change the format you use to store dates, but one workaround would be to build the issue date in the correct format and then do the comparison, also against a date string in the same correct format:
SELECT
issue_date AS count
FROM tablename
WHERE
SUBSTR(issue_date, 7, 4) || '-' ||
SUBSTR(issue_date, 1, 2) || '-' ||
SUBSTR(issue_date, 4, 2) BETWEEN '2016-08-08' AND '2016-09-01'
SQLite's data types does not have a real DATETIME type. It only has NULL, INTEGER, REAL, TEXT and BLOB. Any other type is converted to these, so what it is doing in your case is storing those values as strings, and this comparing as strings.
I personally prefer to store the dates as UNIX timestamps (hence integers) to avoid complicating the SQL queries and simplify the whole thing (although the values in database will become less human-readable).
Because you specified the query with AND. So it matches your query. Use BETWEEN expression.
expression BETWEEN value1 AND value2;
What is wrong with my code:
ExecSql('DELETE FROM STLac WHERE RegN=99 AND BegDate>= 2016-12-14');
This runs, but deletes ALL the rows in STLac for RegN, not just the rows with BegDate on or after 2016-12-14.
Originally I had:
ExecSql('DELETE FROM STLac WHERE RegN=99 AND BegDate>= :myDdate,[myDate]);
which has the advantage I hoped of not being particular to the date format. So I tried the literal date should in the format SQLite likes. Either way I get all rows deleted, not just those on or after the specified date.
Scott S.
Try double quote while putting date. As any value must be provided in between quotes until and unless that column is not int
ExecSql('DELETE FROM STLac WHERE RegN=99 AND BegDate>= "2016-12-14"');
SQLite does not have datetime format as such, so you have to figure out how date is actually represented in the table and change your query to provide the same format. First execute the "select" statement in some kind of management tool,
select * from STLac where RegN = 99 and BegDate >= '2016-12-14' --(or '2016.12.04' or something else)
which displays the result in the grid; when you see the expected rows, change it to "delete" query and copy into your Delphi program.
I am reading a big csv (>1GB big for me!). It contains a timestamp field.
I read it (100 rows to start with ) with fread from the excellent data.table package.
ddfr <- fread(input="~/file1.csv",nrows=100, header=T)
Problem 1 (RESOLVED): the timestamp fields (called "ts" and "update"), e.g. "02/12/2014 04:40:00 AM" is converted to string. I convert the fields back to timestamp with lubridate package mdh_hms. Splendid.
ddfr$ts <- data.frame( mdy_hms(ddfr$ts))
Problem 2 (NOT RESOLVED): The timestamp is created with time zone as per POSIXlt.
How do I create in R a timestamp with NO TIME ZONE? is it possible??
Now I use another (new) great package, PivotalR to write the dataframe to PostGreSQL 9.3 using as.db.data.frame. It works as a charm.
x <- as.db.data.frame(ddfr, table.name= "tbl1", conn.id = 1)
Problem 3 (NOT RESOLVED): As the original dataframe timestamp fields had time zones, a table is created with the fields "timestamp with time zone". Ultimately the data needs to be stored in a table with fields configured as "timestamp without time zone".
But in my table in Postgres the data is stored as "2014-02-12 04:40:00.0", where the .0 at the end is the UTC offset. I think I need to have "2014-02-12 04:40:00".
I tried
ALTER TABLE tbl ALTER COLUMN ts type timestamp without time zone;
Then I copied across. While Postgres accepts the ALTER COLUMN command, when I try to copy (using INSERT INTO tbls SELECT ...) I get an error:
"column "ts" is of type timestamp without time zone but expression is of type text
Hint: You will need to rewrite or cast the expression."
Clearly the .0 at the end is not liked (but why then Postgres accepts the ALTER COLUMN? boh!).
I tried to do what the error suggested using CAST in the INSERT INTO query:
INSERT INTO tbl2 SELECT CAST(ts as timestamp without time zone) FROM tbl1
But I get the same error (including the suggestion to use CAST aargh!)
The table directly created by PivotalR (based on the dataframe) has this CREATE script:
CREATE TABLE tbl2
(
businessid integer,
caseno text,
ts timestamp with time zone
)
WITH (
OIDS=FALSE
);
ALTER TABLE tbl1
OWNER TO mydb;
The table I'm inserting into has this CREATE script:
CREATE TABLE tbl1
(
id integer NOT NULL DEFAULT nextval('bus_seq'::regclass),
businessid character varying,
caseno character varying,
ts timestamp without time zone,
updated timestamp without time zone,
CONSTRAINT busid_pkey PRIMARY KEY (id)
)
WITH (
OIDS=FALSE
);
ALTER TABLE tbl1
OWNER TO postgres;
My apologies for the convoluted explanation, but potentially a solution could be found at any step in the chain, so I preferred to put all my steps in one question. I am sure there has to be a simpler method...
I think you're confused about copying data between tables.
INSERT INTO ... SELECT without a column list expects the columns from source and destination to be the same. It doesn't magically match up columns by name, it'll just assign columns from the SELECT to the INSERT from left to right until it runs out of columns, at which point any remaining cols are assumed to be null. So your query:
INSERT INTO tbl2 SELECT ts FROM tbl1;
isn't doing this:
INSERT INTO tbl2(ts) SELECT ts FROM tbl1;
it's actually picking the first column of tbl2, which is businessid, so it's really attempting to do:
INSERT INTO tbl2(businessid) SELECT ts FROM tbl1;
which is clearly nonsense, and no casting will fix that.
(Your error in the original question doesn't match your tables and queries, so the details might be different as you've clearly made a mistake in mangling/obfuscating your tables or posted a newer version of the tables than the error. The principle remains.)
It's generally a really bad idea to assume your table definitions won't change and column order won't change anyway. So always be explicit about columns. In this case I think your intention might have actually been:
INSERT INTO tbl2(businessid, caseno, ts)
SELECT CAST(businessid AS integer), caseno, ts
FROM tbl1;
Note the cast, because the type of businessid is different between the two tables.
I am using SQLite for a project and < symbol is not working in the query.
There is a table named Holidays which has a field of datatype datetime.
Suppose the table contains some dates of current year in the column HolidayDate.
SELECT HolidayDate
FROM Holidays
WHERE (HolidayDate >= '1/1/2011')
AND (HolidayDate <= '1/1/2012')
The < symbol in the above query is not working. > symbol in the above query is working well.
Please help me.
Try:
SELECT HolidayDate
FROM Holidays
WHERE HolidayDate >= date('2011-01-01')
AND HolidayDate <= date('2012-01-01')
(date format must be YYYY-MM-DD)
There is no datetime datatype in sqlite.
Sqlite only has 4 types:
integeral number
floating-point number
string (stored either as utf-8 or utf-16 and automatically converted)
blob
Moreover, sqlite is manifest-typed, which means any column can hold value of any type. The declared type is used for two things only:
inserted values are converted to the specified type if they seem to be convertible (and it does not seem to apply to values bound with sqlite_bind_* methods at all)
it hints the indexer or optimizer somehow (I just know it has trouble using indices when the column is not typed)
Even worse, sqlite will silently accept anything as type. It will interpret it as integeral type if it starts with "int", as string if it contains "char" or "text", as floating-point number if it is "real", "double" or "number" and as blob if it's "blob". In other cases the column is simply untyped, which poses no problem to sqlite given how little the typing means.
That means '1/1/2011' is simply a string and neither dates in format 'mm/dd/yyyy' nor dates in format 'dd/mm/yyyy' sort by date when sorted asciibetically (unicodebetically really).
If you stored the dates in ISO format ('yyyy-mm-dd'), the asciibetical sort would be compatible with date sort and you would have no problem.