sqlwrite
Description
sqlwrite(
inserts data from a MATLAB® table into a database table with the MATLAB interface to SQLite. If the table exists in the database, this function
appends the data in the MATLAB table as rows in the existing database table. If the table does not exist in
the database, this function creates a table with the specified table name and then inserts
the data as rows in the new table. This syntax is the equivalent of executing SQL statements
that contain the conn
,tablename
,data
)CREATE TABLE
and INSERT INTO
ANSI SQL
syntaxes.
sqlwrite(
specifies the data type for the column in the SQLite database.conn
,tablename
,data
,ColumnType=columntypes
)
Examples
Append Data into Existing Table
Use the MATLAB interface to SQLite to append data from a MATLAB table into an existing table in an SQLite database.
First, create an SQLite connection to the file sample_dataset.db
that contains the table airlinesmall
. The SQLite connection
conn
is an SQLite object.
dbfile = fullfile(matlabroot,"toolbox/database/database/sample_dataset.db");
conn = sqlite(dbfile);
Import the contents of airlinesmall
into MATLAB and display the last few rows.
tablename = "airlinesmall"; query = strcat("SELECT YEAR, MONTH, DayOfMonth, DayOfWeek," + ... "DepTime, ArrTime FROM ", tablename); rows = fetch(conn,query); tail(rows,3)
YEAR MONTH DayofMonth DayOfWeek DepTime ArrTime ____ _____ __________ _________ _______ _______ 2008 2 6 3 1909 2027 2008 2 12 2 718 844 2008 2 15 5 1650 1951
Create a new MATLAB table by extracting the last row and change the departure time by changing
DepTime
to 1950.
data = tail(rows,1); data.DepTime = 1950;
Append the new data table into airlinesmall
by using
sqlwrite
. Then, import the contents of
airlinesmall
into MATLAB again and verify that the last row is the appended data with the updated
departure time.
sqlwrite(conn,tablename,data); rows = fetch(conn,query); tail(rows,4)
YEAR MONTH DayofMonth DayOfWeek DepTime ArrTime ____ _____ __________ _________ _______ _______ 2008 2 6 3 1909 2027 2008 2 12 2 718 844 2008 2 15 5 1650 1951 2008 2 15 5 1950 1951
Close the database connection.
close(conn)
Insert Data into New Table
Use the MATLAB interface to SQLite to insert product data from MATLAB into a new table in an SQLite database.
Create an SQLite connection conn
to the existing SQLite database
file sample_dataset.db
. The SQLite connection is an
sqlite
object.
dbfile = fullfile(matlabroot,"toolbox/database/database/sample_dataset.db");
conn = sqlite(dbfile);
Create a MATLAB table that contains data for two products.
data = table([30;40],[500000;600000],[1000;2000],[25;30], ... ["Rubik's Cube";"Doll House"],'VariableNames',["productNumber" ... "stockNumber" "supplierNumber" "unitCost" "productDescription"]);
Insert the product data into a new database table named
toyTable
.
tablename = "toyTable";
sqlwrite(conn,tablename,data)
Import the contents of the database table into MATLAB and display the rows. The output contains two rows for the inserted products.
rows = sqlread(conn,tablename)
rows=2×5 table
productNumber stockNumber supplierNumber unitCost productDescription
_____________ ___________ ______________ ________ __________________
30 5e+05 1000 25 "Rubik's Cube"
40 6e+05 2000 30 "Doll House"
Delete the new table to maintain the dataset.
sqlquery = "DROP TABLE toyTable";
execute(conn,sqlquery)
Close the database connection.
close(conn)
Specify Column Types When Inserting Data into New Table
Use the MATLAB interface to SQLite to insert product data from MATLAB into a new table in an SQLite database. Specify the data types of the columns in the new database table.
Create an SQLite connection conn
to the existing SQLite database
file sample_dataset.db
. The SQLite connection is an
sqlite
object.
dbfile = fullfile(matlabroot,"toolbox/database/database/sample_dataset.db");
conn = sqlite(dbfile);
Create a MATLAB table that contains data for two products.
data = table([30;40],[500000;600000],[1000;2000],[25;30], ... ["Rubik's Cube";"Doll House"],'VariableNames',["productNumber" ... "stockNumber" "supplierNumber" "unitCost" "productDescription"]);
Insert the product data into a new database table named toyTable
.
Use the ColumnType
name-value argument and a string array to specify
the data types of all the columns in the database table.
tablename = "toyTable"; coltypes = ["numeric" "numeric" "numeric" "numeric" "varchar(255)"]; sqlwrite(conn,tablename,data,ColumnType=coltypes)
Import the contents of the database table into MATLAB and display the rows. The output contains two rows for the inserted products.
rows = sqlread(conn,tablename)
rows=2×5 table
productNumber stockNumber supplierNumber unitCost productDescription
_____________ ___________ ______________ ________ __________________
30 500000 1000 25 "Rubik's Cube"
40 600000 2000 30 "Doll House"
Delete the new table to maintain the dataset.
sqlquery = "DROP TABLE toyTable";
execute(conn,sqlquery)
Close the database connection.
close(conn)
Input Arguments
conn
— SQLite database connection
sqlite
object
SQLite database connection, specified as an sqlite
object created using the sqlite
function.
tablename
— Database table name
string scalar | character vector
Database table name, specified as a string scalar or character vector denoting the name of a table in the database.
Example: "employees"
Data Types: string
| char
data
— Data to insert
table
Data to insert into a database table, specified as a table.
The valid data types in a MATLAB table are:
Numeric array
Cell array of numeric arrays
Cell array of character vectors
String array
Datetime array
Logical array
Cell array of logical arrays
The numeric array can contain these data types:
int8
uint8
int16
uint16
int32
uint32
int64
uint64
single
double
For date and time data, supported formats are:
Date —
'yyyy-MM-dd'
Time —
'hh:mm:ss'
Timestamp —
'yyyy-MM-dd HH:mm:ss'
If the date and time data is specified in an invalid format, then the
sqlwrite
function automatically converts the data to a supported
format.
If the cell array of character vectors or string array is specified in an invalid
format, then the sqlwrite
function enables the database driver to
check the format. If the format is unexpected, then the database driver throws an
error.
You can insert data in an existing database table or a new database table. The data
types of variables in data
vary depending on whether the database
table exists. For valid data types, see Data Types for Existing Table and Data Types for New Table.
Note
The sqlwrite
function supports only the
table
data type for the data
input argument.
To insert data stored in a structure, cell array, or numeric matrix, convert the data
to a table
by using the struct2table
, cell2table
, and array2table
functions, respectively.
Example: table([10;20],{'M';'F'})
Data Types for Existing Table
The variable names of the MATLAB table must match the column names in the database table. The
sqlwrite
function is case-sensitive.
When you insert data into a database table, use the data types shown in the
following table to ensure that the data has the correct data type. This table matches
the valid data types of the MATLAB table variable to the data types of the database column. For example,
when you insert data into a database column that has the BOOLEAN
data type, ensure that the corresponding variable in the MATLAB table is a logical array or cell array of logical arrays.
Data Type of MATLAB Table Variable | Data Type of Existing Database Column |
---|---|
Numeric array or cell array of numeric arrays | DOUBLE |
| VARCHAR |
Logical array | DOUBLE |
Data Types for New Table
The specified table name for the new database table must be unique across all tables in the database.
The valid data types in a MATLAB table are:
Numeric array
Cell array of character vectors
String array
Datetime array
Logical array
The sqlwrite
function ignores any invalid variable types and
inserts only the valid variables from MATLAB as columns in a new database table.
The sqlwrite
function converts the data type of the variable
into the default data type of the column in the database table. The following table
matches the valid data types of the MATLAB table variable to the default data types of the database column.
Data Type of MATLAB Table Variable | Default Data Type of Database Column |
---|---|
Numeric array or cell array of numeric arrays | DOUBLE |
| VARCHAR |
Logical array | DOUBLE |
To specify database-specific column data types instead of the defaults, use the
ColumnType
name-value argument. For example, you can specify
ColumnType="DOUBLE"
to create a DOUBLE
column
in the new database table.
Accepted Missing Data
The accepted missing data for inserting data into a database depends on the data type of the MATLAB table variable and the data type of the column in the database. The following table matches the data type of the MATLAB table variable to the data type of the database column and specifies the accepted missing data to use in each case.
Data Type of MATLAB Table Variable | Accepted Missing Data |
---|---|
Numeric array | NaN |
String array | missing |
Cell array of character vectors | '' |
Datetime array | NaT |
Data Types: table
columntypes
— Database column types
character vector | string scalar | cell array of character vectors | string array
Database column types, specified as a character vector, string scalar, cell array of character vectors, or string array. Use this argument to define custom data types for the columns in a database table. Specify a column type for each column in the table.
Example: ["numeric" "varchar(400)"]
Data Types: cell
| char
| string
Version History
Introduced in R2022a
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