I need to use indexing to query a varchar virtual generated column from a JSON column, but I'm not sure why the index is not being used. Is it because of the varchar type?
Table DDL
create table dp_order
(
id bigint unsigned auto_increment primary key,
detail longtext collate utf8mb4_bin default '{}' not null,
phone_number varchar(20) as (json_value(`detail`, '$.phone_number')),
constraint detail check (json_valid(`detail`))
)
create index dp_order_phone_number
on dp_order (phone_number);
Query
EXPLAIN
(SELECT *
FROM dp_order
WHERE phone_number = '081234567890');
Result
id,select_type,table,type,possible_keys,key,key_len,ref,rows,Extra
1,SIMPLE,dp_order,ALL,dp_order_phone_number,,,,34,Using where
MariaDB version 10.5.12-MariaDB-1:10.5.12+maria~focal
Related
I am learning Azure and data analytics with Azure. Recently finished learning Postgresql.
My question is if there is an alternative to BIGSERIAL data type for Azure Databases. I ran the query (below the error in the following) and had an error. Note that this datatype exists in Postgresql and hence I am getting confused in Azure. Any alternative to BIGSERIAL?
Failed to execute the query. Error: Column, parameter, or variable #1:
Cannot find data type BIGSERIAL.
create table person (
ID BIGSERIAL NOT NULL PRIMARY KEY,
first_name VARCHAR(50) NOT NULL,
last_name VARCHAR(50) NOT NULL,
email VARCHAR(50),
gender VARCHAR(50) NOT NULL,
date_of_birth DATE NOT NULL,
Country_of_birth VARCHAR(50) NOT NULL
);
In PostgreSQL, the SERIAL keyword is used to setup an auto increment column, this works similar to auto increment in SQL. BIGSERIAL is an auto-incremented Bigint column of 8 bytes.
Closest, I could find "bigserial"in MS docs is as here
So...you can use BIGINT instead, below works fins for me.
create table person (
ID BIGINT NOT NULL PRIMARY KEY,
first_name VARCHAR(50) NOT NULL,
last_name VARCHAR(50) NOT NULL,
email VARCHAR(50),
gender VARCHAR(50) NOT NULL,
date_of_birth DATE NOT NULL,
Country_of_birth VARCHAR(50) NOT NULL
);
hi please how do i give sql column maximum input example if i want max_num column to take only three(3) result sets or inputs
It's mostly the same in other rdbms. You need to specify right after the column type
MYSQL
CREATE TABLE TestTable(
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
three_char_demo VARCHAR(3) NOT NULL,
)
PostgreSQL
CREATE TABLE TestTable(
ID INT PRIMARY KEY NOT NULL,
three_char_demo CHAR(3) NOT NULL,
);
CREATE TABLE employees (
id INT NOT NULL auto_increment PRIMARY KEY (ID),
first_name VARCHAR(20) DEFAULT NULL,
last_name VARCHAR(20) DEFAULT NULL,
salary INT DEFAULT NULL);
I think this is correct query to create table in Oracle database.. but it gives the following error:
ORA-00907: missing right parenthesis
How to correct the statement?
You can validate your SQL using formatting tools such as http://www.dpriver.com/pp/sqlformat.htm
auto_increment seems like a proprietary MySQL extension, so it's not valid for Oracle.
also, "id int not null auto_increment primary key (id)" does not need the last "(id)"
Using Oracle, you shoud try something like this
CREATE SEQUENCE seq;
CREATE TABLE employees
(
id INTEGER NOT NULL PRIMARY KEY,
first_name VARCHAR2(20) DEFAULT NULL,
last_name VARCHAR2(20) DEFAULT NULL,
salary INTEGER DEFAULT NULL
);
INSERT INTO employees
VALUES (seq.NEXTVAL,
'name',
'last name',
1);
Sometimes, SQL is fancy, because even having a standard (ANSI), most DBMS vendors add their proprietary extensions to the SQL creating their own languages, so it's rare the situation where you can port one SQL from one DB into another without any changes.
Also, it's a pretty useless error message. It could at least say which position. (also, there's no missing parenthesis, but an unexpected token)
EDITED : New feature 12c
CREATE TABLE employees(
id NUMBER GENERATED ALWAYS AS IDENTITY,
first_name VARCHAR2(30)
etc.
);
Why would you do default null?
The VARCHAR datatype is synonymous with the VARCHAR2 datatype. To avoid possible changes in behavior, always use the VARCHAR2 datatype to store variable-length character strings.
Replace
id INT NOT NULL auto_increment PRIMARY KEY (ID),
with
id INT NOT NULL auto_increment PRIMARY KEY,
this is more efficient
CREATE TABLE EMPLOYEES_T(
ID NUMBER,
FIRST_NAME VARCHAR2(20) DEFAULT NULL,
LAST_NAME VARCHAR2(20) DEFAULT NULL,
SALARY INTEGER DEFAULT NULL,
CONSTRAINT PK_EMPLOYEES_T PRIMARY KEY(ID)
);
CREATE DATABASE agom COLLATE Arabic_CI_AS
CREATE TABLE Branches
(
ID INT PRIMARY KEY NOT NULL IDENTITY,
NAME VARCHAR(255) NOT NULL
)
CREATE TABLE agom.Brands
(
ID INT PRIMARY KEY NOT NULL IDENTITY,
NAME VARCHAR(255) NOT NULL
)
CREATE TABLE agom.Work_Order
(
NUMBER INT NOT NULL,
BRANCHID INT NOT NULL,
BRANDID INT NOT NULL,
WDATE DATE NOT NULL,
REPAIRSTATUS VARCHAR(255),
REPAIRCOST VARCHAR(255),
REMARK VARCHAR(500),
PRIMARY KEY (NUMBER,BRANCHID,BRANDID)
)
CREATE TABLE agom.Profiles
(
ID INT PRIMARY KEY NOT NULL IDENTITY,
USERNAME VARCHAR(25) NOT NULL,
PASS VARCHAR(25) NOT NULL
)
ALTER TABLE agom.Work_Order
ADD CONSTRAINT branchfk
FOREIGN KEY (BRANCHID) REFERENCES Branches(ID)
ALTER TABLE agom.Work_Order
ADD CONSTRAINT brandfk
FOREIGN KEY (BRANDID) REFERENCES Brands(ID)
I get an error that cannot create table
I try to write database name with the table name db.tablename but it's not working
I need to create the database then create the tables and its constraints but I don't know where is the error.I am a sql noob
It's never Database.Table.
It's either Table, or Schema.Table, or Database.Schema.Table, or Server.Database.Schema.Table.
You probably just want to insert USE agom right after create database, and then only refer to tables by name.
Alternatively, you can refer to your tables as agom.dbo.Work_Order, dbo being the default database schema.
See Using Identifiers As Object Names for general reference.
I'm getting this error in puTTY. Not sure why, looks right to me ...
psql:pierre.sql:10: ERROR: syntax error at or near "AUTO_INCREMENT"
LINE 2: c_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
^
psql:pierre.sql:18: ERROR: syntax error at or near "AUTO_INCREMENT"
LINE 2: r_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
--DROP TABLE customer, reservation;
CREATE TABLE customer(
c_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
c_ref VARCHAR(30) NOT NULL,
f_name VARCHAR(30) NOT NULL,
l_name VARCHAR(30) NOT NULL,
address VARCHAR(100) NOT NULL,
email VARCHAR(100) NOT NULL,
phone VARCHAR(11) NOT NULL
);
CREATE TABLE reservation(
r_id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,
c_id VARCHAR(30) NOT NULL REFERENCES customer(c_id),
book_date DATE NOT NULL CHECK (book_date <= now()),
s_time DOUBLE NOT NULL,
e_time DOUBLE NOT NULL,
amount INTEGER NOT NULL
);
Any ideas why?
auto_increment looks like something you'd use with MySQL.
But, here, it seems you are using PostgreSQL.
According to the datatype serial section of the manual, postgresql's equivalent of auto_increment is serial or bigserial.
Quoting that page :
The data types serial and bigserial are not true types, but merely
a notational convenience for setting up unique identifier columns
(similar to the AUTO_INCREMENT property supported by some other databases).
In Postgres 10 or later consider an IDENTITY column:
CREATE TABLE customer(
c_id INTEGER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
...
(PRIMARY KEY also makes it NOT NULL automatically.)
Details:
Auto increment table column
In Postgres 9.6 or older consider a serial like Pascal already suggested.
Works in pg 10 or later, too, but IDENTITY is generally superior.