Field adding method and system of database

The embodiment of the invention discloses a field adding method and a system of a database and is applied to the technical field of information processing. If a new field is added into a to-be-operated table of the database, when the system receives a command of adding the field into the to-be-operated table of the database, definition information of the field to be added is added into the database according to information of the field to be added, the number of fields included in the to-be-operated table is modified correspondingly, and then the to-be-operated table with the added field is displayed to a user, including the field to be added, wherein the command comprises the information of the to be added field. In the method and the system, the new field can be added only by adding the definition information of the field to be added into the database and modifying the number of the fields, that is to say, modification is carried out based on the original to-be-operated table, and new ...

Data backup and recovery methods and devices

The invention provides a data backup method. The data backup method comprises the steps that the size and the total line number of a table not backed up in a database are obtained; the target line number of given structural query language sentences contained in each fragment of the table which is not backed up is calculated according to the total line number and the value of a preset first instruction line option; when the size of the table not backed up is larger than or equal to the value of a preset second instruction line option, the table not backed up is divided into a plurality of fragments according to the total line number and the target line number, and a fragment backup file of each fragment is generated and output. The invention further provides a data recovery method, a data backup device and a data recovery device. The data backup and recovery methods and devices can improve the speed of data recovery and improve the efficiency of data processing.

Technology of making refined benzene by hydrogenation, desulfurization and denitrification of coking benzene

Carbonylation reaction system and method based on series connection of multiple kettles

The invention discloses a carbonylation reaction system and method based on series connection of multiple kettles, belongs to the technical field of chemical engineering, and solves the technical problem that the requirements of reaction for preparing methyl propionate through ethylene carbonylation and separation and purification on kettle liquid composition are low. The system comprises a reaction kettle A, a reaction kettle B connected out of the reaction kettle A, an evaporator connected out of the reaction kettle B, a rectifying tower connected out of the evaporator, and a methyl propionate product output pipe connected out of a tower kettle of the rectifying tower, and the reaction kettle A is connected with a material conveying pipe. The method mainly comprises the following steps: conveying raw materials to a reaction kettle A for rapid ethylene carbonylation reaction, and then conveying the raw materials to a reaction kettle B for ethylene carbonylation reaction with improved methyl ...